The Gemara explains the reference to this particular donkey. The donkey of Rabbi Pinehas ben Yair was stolen by robbers one night. It was kept hidden by them for three days, and yet it did not eat anything. After three days, they reconsidered and decided to return it. They said: Let’s get it out of here, so that it shouldn’t die in our possession and leave a stench in our cave. When they set it free it went and stood by its master’s gate and began braying. Rabbi Pinehas said to the members of his household: Open up for that poor creature, which has gone three days without eating anything. They opened the gate for it, and it entered Rabbi Pinehas’ courtyard.He told them: Give it something to eat. They placed barley before it, but it would not eat. They said to him: Rabbi, it will not eat. He said to them: Has the barley been tithed so that it is fit to eat? They replied: Yes. He then asked them: And have you separated their doubtfully tithed produce? Did you tithe the grain about which there is doubt as to whether it has been tithed properly?They replied: Didn’t you teach us the following, Rabbi: One who purchases grain for feeding an animal, or flour for processing animal hides, or oil for lighting a lamp, is exempt from separating doubtfully tithed produce? There is no need to separate tithes from doubtfully tithed produce to feed a donkey. He said to them: What can we do for that poor creature, which is very strict with itself and will not eat even from doubtfully tithed produce, despite this exemption? And they therefore separated tithes from the doubtfully tithed produce, and the donkey finally ate the barley grains.
Rabbi Pinehas ben Yair was one of the Tanna’im who was known as one of the righteous people of his generation and as a miracle worker. He was related by marriage to Rabbi Shimon bar Yohai (according to some texts he was his father-in-law, according to others, his son-in-law). During his lifetime he was already spoken about as a legend, and the Gemara is replete with miraculous stories about him to the extent that the Sages say, “How much greater was this man than Moshe Rabbenu!” Nevertheless, only a small number of his teachings are recorded in the Gemara.