Tractate Peah - Chapter 5 - Mishnah 4

A property owner who was passing from place to place and need to take gleanings, the forgotten sheaf, peah or the poor man’s tithe, he may take them, and when he returns home, he must pay [for the amount gathere], the words of Rabbi Eliezer. The sages say: he was a poor man at that time [and so he need not make restitution].