Several cases in Gemara of ליפנים משורת הדין. Difference between if one is חייב בדיני שמים or 50/50. Are you morally obligated to pay? Is it a requirement? Can Beis Din force? Does Tefisah work?
Tosfos, R' Shimon Shkop, R' Asher Weiss, Rabbeinu Yerucham, Rosh, Mordechai, Pischei Teshuvah, Bach, Shach, Maharshal, Rashi, Ktzos, Rabbi Akivah Eiger, Tur.
2-11-24