This is a long drawn out litigation that has lasted many years; in its first phase,  it has  involved a  long decision by  the  Court of Appeals and an  eight-page  decision  of this Tribunal;  and in  its second  phase, an  eleven-page decision of the same Court of Appeals and a resolution of this Tribunal dismissing a petition for certiorari to review said last decision  of the Court of Appeals.   The third phase of the litigation is the present petition for mandamus to compel the lower court to approve the record on appeal filed by petitioners, wherein they tried to appeal the order of  execution  of the trial court  to implement the  last decision of the Court of Appeals.

For a clear and comprehensive statement of the first part of the history of this case, as well as the issues involved therein  and the determination thereof, we  can  do no better than reproduce  a pertinent portion  of the  well written second  decision of the Court of  Appeals,  penned by Justice Felipe Natividad,  based  in part  on our aforementioned decision  in  the first phase of the litigation:

"This case is once more before this Court on the appeal taken by the plaintiffs from an order of the  Court of First Instance of Manila fixing the value of the two  buildings involved therein  at P50,000 and providing that the plaintiffs  should  pay  that  amount to  the defendants  if they desire  to  appropriate  said buildings.

"The  records  disclose that prior  to  the year  1930  defendant Joaquin C.  Yuseco,  an  attorney-at-law, had been rendering without compensation  professional services to Maria  Lim.  To  show  her appreciation of such services,  Maria Lim offered  to  Joaquin C. Yuseco and his wife, defendant  Rosario Yuseco, for them to build a  house thereon, Lots 11-A and  11-B, Block 2251, of the Hacienda de San Lazaro, registered in her  name under  Transfer Certificate of Title Nos. 36400 and 36401,  Office of  the Register of Deeds of the City  of Manila. The Yusecos accepted the offer,  and in the middle  part of that year they built a dwelling  house and an annex for garage and servant  quarters on said  lots.  To legalize  the possession of said lots by the Yusecos, Maria Lim and the Yusecos executed  a  contract of lease covering them, which  was to run  for a  period of five years,  with a yearly rental of  P120.

"On  November  29,  1945,  a few days  before her death,  Maria Lim sold the  two lots  above referred to to her daughter, plaintiff Belen  Uy Tayag,  married to  Jesus B.  Tayag, for  the sum of P4,000.  In  the year 1946,  the Tayags asked the Yusecos to remove their  house from the lots, or else  pay to them a monthly rent of P120 therefor.  The latter  refused.  Because of this  attitude of  the Yusecos, the Tayags brought against the latter in the Municipal Court of the city of Manila an action of ejection for the restitution of the lots  to them and the recovery of a monthly  rental of P500 from November 30, 1945, up to the date of the restitution.  Judgment was rendered in that court in favor  of the plaintiffs.  The defendants appealed.

"The case was duly  tried in the  Court  of First Instance of Manila.  After such trial, that court rendered judgment adjudicating to  the plaintiff Belen Uy Tayag the possession  of the two lots involved in the action, with right to appropriate the two  building is existing thereon  upon  payment  to the  defendants  of their value, which  it assessed at the sum of  P50,000, and providing that should the plaintiffs  fail to pay this  amount within  90  days after  the decision shall have become  final, the defendants  shall have the  right to  purchase said lots for the sum  of  P10,000  to  be paid within 90 days from the date the plaintiffs  shall have failed  to buy  the buildings.  From this judgment,  the plaintiffs appealed.

"The Court of Appeals, finding that the defendants were possessors of the lots in good faith, affirmed the judgment of the  Court of First Instance of  Manila.   Not satisfied with this judgment, the plaintiffs appealed  therefrom  by  certiorari to  the  Supreme  Court.   The latter, after due hearing, rendered judgment,  the dispositive  part of which  reads  as  follows:

"Affirming the decision of the Court  of Appeals in  so  far as  it finds  and declares  respondents to  be  possessors in  good  faith, let this case be remanded to  the  trial court for further  proceedings,  particularly to  give an  opportunity to plaintiffs-petitioners to  exercise  their  choice  and  option;  and for  purpose  of   said choice and  option  the trial court  will  admit evidence  and make a  finding as to the  amount  of the useful expenditures  or   "the increase in  value which the thing  has acquired by reason thereof", under Art.  453  of the  old  Civil  Code, to be  refunded  or   paid by  the petitioners should they choose to appropriate the buildings; "the  value  of the  land" under Art. 361  of the same  Code,  to be  paid by  the  defendants-respondents in case plaintiffs-petitioner? elect  to compel  them  to  buy the land.   No costs."

"Upon  the case being  remanded to the Court  of First Instance, of  Manila,  the latter,  in consonance  with the  Directive  of the Supreme  Court, issued  on July 11,  1956,  an  order requiring the plaintiffs to make  their  choice in  writing within 10 days whether they  would  purchase the buildings erected on the lots,  or  allow the defendants to buy said lots, and set the case for  hearing on August 3, 1956, for the reception of the evidence of the parties regarding the value of said  lots and  buildings.  Complying with this order, on  July 20, 1956, the plaintiffs, through counsel, filed  a  manifestation  stating that

"they  are not willing  to sell the  lot involved in  this  case, but that they are willing to appropriate the building erected thereon if  its valuation  is  as it should be and is  properly and fairly determined pursuant to, and  in accordance with the  evidence and the  law."

On August  3, 1956, when the case was  called for hearing, the  trial court, in  open court,  issued the following order:

'Considering  that  choice  made by  the plaintiffs, the  Court is of the opinion that the next step now is to adduce  evidence in  connection  with the value of the buildings erected on the  land pursuant to the  dispositive  part  of the decision of  the Supreme Court.  And the  Court believes that under the circumstances since the  defendants will be the  sellers,  they have  the burden  of proving the value  of the buildings  which  belong to  them, giving the plaintiffs  opportunity to offer their own  evidence as rebuttal. That is the ruling of the Court.'

The plaintiffs  asked for a  reconsideration of this order, and  for the issuance of another allowing them  to  adduce evidence on  the value of the buildings as well as the lots.   This motion was denied.

"The case was  finally heard  in, the Court of First Instance of Manila on  August  23  and  24,  1956.   Evidence was  presented in said hearings by  the plaintiffs  and the defendants.  The evidence of the plaintiffs tends to show that the value  of the  two buildings erected on the lots in question cannot  be more than P40,000.  That of the  defendants,  on the other  hand,  establishes that the value of the chalet erected on the lots was  from P45,000 to P50.000,  and of the garage and dwelling house, from P5.000  to P6,000.  Upon  the evidence thus submitted, the trial court, in its order of August  28, 1956, fixed the reasonable value  of the two buildings on the lots at P50,000, and ordered that  that  amount  should  be  paid  by  the plaintiffs to the  defendants  if they  desire  to  appropriate said buildings.  This is the  order  appealed from.

"Appellants concede that the fact that the appellees were possessors in good faith of the lots in  question is res judicata between  the parties.  They contend,  however, first,  that the trial court erred in limiting the  reception of the evidence  to the value of the buildings erected  on the lots in  question, instead of admitting evidence  on the value of both  said lots and buildings; and, second,  that the trial court erred in assessing at  P50,000  the  value of the  two buildings on said  lots.

"1.  Appellants contend under the first proposition that the decision of the Supreme Court of October 24, 1955, affirming the finding of the Court of Appeals that the appellees  were possessors of the lots in question in good faith and  ordering the remand of the case to the court of origin,  contemplates the reception of evidence   as to the values of  both said lots' and the buildings  existing thereon irrespective of the choice and option  the  appellants  may exercise in the premises, and,  consequently, the trial court, in limiting  the reception of  evidence on the value of  the buildings, failed to fully implement the  instructions of the Supreme Court.

"We do not  share appellants'  view.  The pertinent part of  the decision of the Supreme  Court of October 24, 1955, reads as follows:

" '* * * and   for  purposes   of  said  choice  and  option   the trial court will admit evidence and make a  finding as to the amount of  the useful expenditures  or  "the  increase in  value  which the thing has  acquired  by reason . thereof",  under Art. 453: of  the old  Civil Code, to be  refunded or paid by the petitioners should they choose to appropriate the  buildings;  "the value of the land" under  Art. 361  of the same Code, to be paid by the defendants-respondents in  case plaintiffs-petitioners  elect to compel them to buy the land.'

"It will be noted that the directive made in the above decision is in  alternative. The clause having reference to the admission of evidence regarding  the value  of the buildings is separated  by a semi-colon from the clause  referring to the value  of the  lots on which said buildings are erected; and the first clause ends with tho phrase 'to be refunded or paid to the petitioners should they choose to appropriate  the  buildings', while the second clause  terminates with  the phrase 'to be paid by the defendants respondents  in  case plaintiffs-petitioners  elect  to compel  them  to  buy  the  land.' It would seem clear, therefore,  from the language of the decision  that evidence as to the value of  said buildings should  be admitted' only if the appellants choose to appropriate  the buildings, and that, in case the appellants  should elect to compel the  appellees to buy the lots,  then  evidence  concerning  the value  of said  lots must be admitted. This, in  our opinion, is the most sensible construction that could be given to the decision above referred  to.  Any other construction would bring about unnecessary confusion  in the evidence, to say nothing of the valuable time  of the Court that  will necessarily be wasted. For, it stands  to  reason, that  if the appellants chose not to  sell the lots  to  the appellees and  to  appropriate  the buildings, which cannot be  ordered removed by  the  builders, the thing in order would be the reception of evidence having reference to the value of  said buildings  only.  Evidence as to  the value of the lots  would  be superfluous, impertinent  and immaterial.   This was what the trial court did.  We, therefore, find  the action of the trial court complained  of in accordance with law." * * *

Under  the second  decision of  the Court of  Appeals,  the value of the two buildings in  question fixed by  the trial court at P50,000 was reduced to P47,500.   With that modification, the decision of the trial court was affirmed.   As already stated, petitioners herein filed with us a petition for  certiorari to  review said decision  of the Court  of Appeals, but we dismissed said petition for lack of merit. In other words, we found said decision to be correct.

When said  decision  finally reached  the  trial  court, the latter issued  the corresponding writ of  execution to collect  from petitioners the sum of P47,500 for the  buildings  in litigation.   Petitioners protested the  writ of execution,  claiming  that  it varied the  terms  of the  final decision, and  upon denial of their petition for reconsideration, tried to appeal therefrom by preparing the corresponding record  on appeal.  The  trial  court refused to approve the record on  appeal, saying that the order for the writ of execution issued by it was fully in accordance with the  terms of the decision.   Hence, the present petition  for  mandamus  to  compel the trial  court  to elevate the case to us on appeal.

We are satisfied that the trial court' acted correctly in ordering  the  writ of execution  to issue.  The  main contention of herein petitioners is  that they still  retain the right of option, that is to say, to make a choice of either buying the house or compelling  the  owners thereof to buy the land; and that  furthermore, even if they already had made that choice, nevertheless, they cannot be compelled to pay the price fixed by the courts for the purchase of  the  said houses, because of their inability to  pay the said  price.  We  find  both  arguments   untenable.  The question of whether petitioners had  finally  made their choice,  namely, to buy the houses because they were  unwilling to sell the land, was directly in issue before the Court of Appeals which definitely decided that petitioners had made their choice not to sell their  land but to buy the houses built thereon.   As we have  already said, by our refusal to review said decision of the Court of Appeals, we agreed with the said court on its stand on this point; consequently, the trial court was fully warranted in limiting the presentation  of evidence to the value of the said houses, not of the land.

As  regards the alleged inability of petitioners to pay the value  of the buildings finally fixed by the courts at P47,500, claimed by them to be a good reason for not compelling them to buy the buildings,  we cannot sanction  said theory. Otherwise, were that claim or contention to be sustained, and if  petitioners were allowed to change their mind, repudiate  their choice made in court not to sell the land but to buy the buildings, and then  compel the owners of the houses, respondents herein, instead to buy land, then what if respondents also claimed  inability to pay the price of the land, claiming that it is also a good and valid reason for not  compelling them  to make the  purchase?  How would this litigation end, if it ever would end?

We hold that once a party, in conformity with a court decision,  has  made his choice, and has duly  informed the court of said  choice,  and  is accordingly  ordered to comply  with the  same by  buying the  building erected on  his land and pay the value thereof fixed by the courts, that duty is converted into a money obligation which can be  enforced by execution,  regardless of the unwillingness and alleged inability of the party concerned to  pay the amount.   Here there is a final decision of the petitioners to buy the houses and pay the value thereof.  If petitioners were ready, willing and able to pay the amount, there would be  no need for execution.  It is precisely because they are unwilling and allegedly unready and unable to pay the sum, that  execution issues.  That is part of  the judicial  machinery  of due process in  action,  and  we find nothing wrong in it.

As to the alleged absence in the order of execution for the houseowners to make the transfer of  the houses to the petitioners, that is to be understood, that upon  full payment of the price of the  houses, the respondents herein will make and  execute the corresponding deed of transfer.

In  view  of the  foregoing, the petition for mandamus is  hereby denied,  with costs.  The  writ of preliminary injunction heretofore issued is hereby ordered dissolved.

Paras, C, J., Bengzon, Padilla, Reyes, A., Bautista Angelo, Labrador, Concepcion,  and Endencia, JJ., concur.