Reference for Bava Metzia 40:2

א"ל רב עמרם לרבה היכי פשיט מר איסורא מממונא א"ל תרדא שטרי חליצה ומיאונין תנן

R. Amram then said to Rabbah: How does the Master derive a law relating to a religious prohibition from a civil law?<span class="x" onmousemove="('comment',' In the sentence quoted from the Mishnah the reference is obviously to documents regarding commercial transactions and similar matters falling within the scope of civil law, while the question of the validity of a divorce is one ultimately affecting a moral or religious issue, and one may not derive one from the other. Cf. Ber. 19b. ');">²</span>

Jastrow