Reference for Bava Metzia 71:14
אי הכי לבעלים בעי לשלומי דאמרו ליה לדעתך
R. Hisda said: This ruling of Rab was not stated explicitly, but by implication. For there were certain gardeners who used to deposit their spades every day with a particular old woman. But one day they deposited them with one of themselves. Hearing the sounds of a wedding, he went out and entrusted them to that old woman. Between his going and returning, their spades were stolen, and when he came before Rab, he declared him not liable. Now, those who saw this thought that it was because if a bailee entrusts [the bailment] to another bailee he is free [from liability]; but that is not so: there it was different, Seeing that every day they themselves used to deposit [their spades] with that old woman.