There are four classes of people who are entrusted with items of value (Bava Metzia 7:8, Shevuot 8:1): one who looks after it as a favour, one who does so for a fee, one who borrows it and one who ...
In masechet shevuot, 41b, the gemara discusses a case of a loan as follows (h/t dafyomi.co.il) Levi lent Yehudah, and told him 'repay me in front of two witnesses who learn Halachah. Yehudah ...
I know that one of the reasons given for our being limited by miderobonon laws is explained in Masechet Shevuot, 39a which says as follows (lifted from dafyomi.co.il) i. "Asher Yeshno Po ha'Yom"...