עַל־פִּ֣י שְׁנַ֣יִם עֵדִ֗ים א֛וֹ שְׁלֹשָׁ֥ה עֵדִ֖ים יוּמַ֣ת הַמֵּ֑ת לֹ֣א יוּמַ֔ת עַל־פִּ֖י עֵ֥ד אֶחָֽד׃
A person shall be put to death only on the testimony of two or more witnesses; no one shall be put to death on the testimony of a single witness.—
Torah Temimah points to Sanhedrin (Rav Nachman on combined testimony).
אמר רב נחמן, עדות מיוחדת כשרה בדיני ממונות, דכתיב לא יומת על פי עד אחד, בדיני נפשות הוא דאין כשרה, אבל בדיני ממונות כשרה.
English: Rav Nachman said: Combined (disjoint) testimony is valid in monetary cases, for it is written “he shall not be put to death on the testimony of a single witness” — it is only in capital cases that it is invalid; but in monetary cases it is valid.
The restriction of “one witness” is limited to capital cases; in monetary matters two witnesses may testify to separate aspects of the same event and still combine.
Derash on the verse (Bavli) — not a formal named middah of the 13. The negative formulation “shall not be put to death” is taken to confine the stricter rule to capital law.
In capital cases the two witnesses must form a single coherent unit of testimony; in monetary cases disjoint or sequential testimony may still combine to establish liability.