Well-settled is the rule that the Supreme Court is not a trier of facts. When supported by substantial evidence, the findings of fact of the Court of Appeals are conclusive and binding on the parties and are not reviewable by this Court, unless the case falls under any of the following recognized exceptions

See - Substantial Compliance Rule In Formalities Of Wills... - The Lawyer's Post

"x x x.

We find that the issues raised by petitioner concern pure questions of fact, which may not be the subject of a petition for review on certiorari under Rule 45 of the Rules of Civil Procedure.

The issues that petitioner is raising now i.e., whether or not the will was signed by the testator in the presence of the witnesses and of one another, whether or not the signatures of the witnesses on the pages of the will were signed on the same day, and whether or not undue influence was exerted upon the testator which compelled her to sign the will, are all questions of fact.

This Court does not resolve questions of fact in a petition for review under Rule 45 of the 1997 Rules of Civil Procedure. Section 1⁠1 of Rule 45 limits this Court’s review to questions of law only.

Well-settled is the rule that the Supreme Court is not a trier of facts. When supported by substantial evidence, the findings of fact of the Court of Appeals are conclusive and binding on the parties and are not reviewable by this Court, unless the case falls under any of the following recognized exceptions:

(1) When the conclusion is a finding grounded entirely on speculation, surmises and conjectures;

(2) When the inference made is manifestly mistaken, absurd or impossible;

(3) Where there is a grave abuse of discretion;

(4) When the judgment is based on a misapprehension of facts;

(5) When the findings of fact are conflicting;

(6) When the Court of Appeals, in making its findings, went beyond the issues of the case and the same is contrary to the admissions of both appellant and appellee;

(7) When the findings are contrary to those of the trial court;

(8) When the findings of fact are conclusions without citation of specific evidence on which they are based;

(9) When the facts set forth in the petition as well as in the petitioners’ main and reply briefs are not disputed by the respondents; and

(10) When the findings of fact of the Court of Appeals are premised on the supposed absence of evidence and contradicted by the evidence on record.⁠2 

x x x."

See:
SECOND DIVISION, G.R. No. 145545, June 30, 2008, PAZ SAMANIEGO-CELADA, PETITIONER, VS. LUCIA D. ABENA, RESPONDENT.