Gittin 29A

אבל בבית דין של ישראל, כיון דנפק ליה דינא לקטלא ⁠– קטלי ליה.

but in a Jewish court, once his verdict to be executed has emerged, they execute him.

אמר ליה אביי: בית דין של ישראל נמי, אפשר דחזו ליה זכותא! כי חזו ליה זכותא ⁠– מקמי דליגמר דינא, בתר גמר דינא ⁠– תו לא חזו ליה זכותא.

Abaye said to him: In a Jewish court as well, it is possible that the court will see fit to acquit him afterward and he will be released. Rav Yosef said: When the court sees fit to acquit him, it is before the verdict; after the verdict the court will not further see fit to acquit him, as it is uncommon for the court to find a reason to acquit him after his verdict has been delivered.

לימא מסייעא ליה: כל מקום שיעמדו שנים ויאמרו ״מעידים אנו את איש פלוני שנגמר דינו בבית דינו של פלוני, ופלוני ופלוני עדיו״⁠ – הרי זה יהרג! דלמא בורח שאני.

The Talmud suggests: Let us say that a Mishnah (Makkot 7a) supports Rav Yosef’s opinion: Concerning one who fled from the court after his verdict was issued, the Mishnah states: Any place where two witnesses arise and say: We testify about so-and-so that his verdict was finalized in the court of so-and-so, and so-and-so and so-and-so were his witnesses, the halakha is that this person should be killed. It is evident from the Mishnah in tractate Makkot that there is no concern that the court might later have found a reason to release him. The Talmud answers: Perhaps one who flees is different, as the court will not reconsider his verdict once he has fled.

תא שמע: שמע מבית דין של ישראל שהיו אומרים ״איש פלוני מת״; ״איש פלוני נהרג״⁠ – ישיאו את אשתו. מקומנטריסים של גוים ״איש פלוני מת״; ״איש פלוני נהרג״⁠ – אל ישיאו את אשתו.

The Talmud suggests another proof: Come and hear: If one heard from a Jewish court that they were saying: The man so-and-so died, or: The man so-and-so was killed, then the court allows his wife to marry. If he heard from a non-Jew judicial registrar: The man so-and-so died, or: The man so-and-so was killed, then the court does not allow his wife to marry.