Commentary for Sotah 3:13

או אינו אלא אפילו באחד ת"ל (דברים יט, טו) לא יקום עד אחד באיש

the house of C is for D; the field of E is for F! — There is no contradiction, the latter dictum referring to a first marriage and the former to a second marriage. R. ELIEZER SAYS, HE WARNS HER ON THE TESTIMONY OF TWO WITNESSES etc. So far only do [R. Eliezer and R. Joshua] differ, viz. in the matter of warning and seclusion, but in the matter of misconduct [they agree] that one witness is believed.<span class="x" onmousemove="('comment',' [After due warning had been given and seclusion taken place]. And without drinking the water she leaves her husband's house and does not receive what would normally have been due to her under the marriage-contract. ');">²²</span> We similarly learn in the Mishnah: If one witness says: I saw that she committed misconduct, she does not drink the water.<span class="x" onmousemove="('comment',' Infra 31a. ');">²³</span> Whence is it derived according to Torah-law that one witness is believed? As our Rabbis taught: And there be no witness against her<span class="x" onmousemove="('comment',' Num. V, 13. ');">²⁴</span> — the text refers to two witnesses.<span class="x" onmousemove="('comment',' I.e., wherever Scripture uses the word witness, even in the singular, it denotes two. ');">²⁵</span> But perhaps it is not so and even one [suffices]! There is a teaching to declare, One witness shall not rise up against a man.<span class="x" onmousemove="('comment',' Deut. XIX, 15. ');">²⁶</span>

Rashi on Sotah