Hazrat Abdullah bin Ubaidullah bin Abbas narrates that we were sitting with Sayyiduna Ibn Abbas (may Allah be pleased with them). He said, "By Allah, the Messenger of Allah (peace and blessings be upon him) did not distinguish us from the people with anything except three things: He commanded us to perform complete ablution, not to eat charity, and not to mate a horse with a donkey." Musa says that I met Abdullah bin Hasan, so he said, "Abdullah bin Ubaidullah narrated this hadith to me in this way." He said that there was a shortage of horses among Banu Hashim, so the Prophet (peace and blessings be upon him) wished that they would increase. (That is why he forbade mating with donkeys.)