Makkot 6B

מתני׳ היו שנים רואין אותו, מחלון זה, ושנים רואין אותו מחלון זה, ואחד מתרה בו באמצע, בזמן שמקצתן רואין אלו את אלו ⁠– הרי אלו עדות אחת, ואם לאו ⁠– הרי אלו שתי עדיות. לפיכך, אם נמצאת אחת מהן זוממת ⁠– הוא והן נהרגין, והשניה פטורה.

Mishnah: In a case where there were two witnesses observing an individual violating a capital transgression from this window in a house, and two observing him from that window in a house, and one person was forewarning the transgressor in the middle between the two sets of witnesses, the halakha depends on the circumstances. In a situation where some of the witnesses observing from the two windows see each other, the testimony of all these witnesses constitutes one testimony, but if they do not see each other, the testimony of these witnesses constitutes two independent testimonies. Therefore, as two independent sets of witnesses, if one of the sets was found to be a set of conspiring witnesses, while the testimony of the other set remained valid, both he, the one accused of violating the capital transgression, and they, the conspiring witnesses, are executed, and the second set, whose testimony remained valid, is exempt.

רבי יוסי אומר: לעולם אין נהרגין עד שיהו שני עדיו מתרין בו, שנאמר ״על פי שנים עדים״. דבר אחר: ״על פי שנים עדים״⁠ – שלא תהא סנהדרין שומעת מפי התורגמן.

R' Yosei says: Transgressors are never executed unless his two witnesses are the ones forewarning him, as it is stated: “At the mouth of two witnesses…he who is to be put to death should die” (Deuteronomy 17:6), from which it is derived that it is from the mouths of the two witnesses that the accused must be forewarned, and forewarning issued by someone else is insufficient. Alternatively, from the phrase “at the mouth of two witnesses” one derives that the judges must hear the testimony directly from the witnesses, and the Sanhedrin will not hear testimony from the mouth of an interpreter.