Reference for Arakhin 44:6

בשלמא לרב הונא בריה דרב יהושע מוקי לה בשחייב מודה אלא לרב פפא קשיא

But according to R'Papa this will present a difficulty? - R'Papa will tell you: If you like, I can tell you the reference is to a kethubah, the reason being 'for favour's sake'! Or if you like, I can tell you the reference i a heathen creditor who accepted upon himself to have his case dealt with in accord with Israelite law.

Jastrow