Musnad Ahmad 20:5

Yazid narrated to us, Mahdi ibn Maymun informed us, from Muhammad ibn Abi Ya’qub, from al-Hasan ibn Sa’d, from ‘Abdullah ibn Ja’far. And Bahz and ‘Affan narrated it to us, they said: Mahdi narrated to us, Muhammad ibn Abi Ya’qub narrated to us, from al-Hasan ibn Sa’d, the freed slave of al-Hasan ibn ‘Ali, from ‘Abdullah ibn Ja’far, who said: The Messenger of Allah (may Allah bless him and grant him peace) made me ride behind him one day, and he whispered a hadith to me that I would not tell to anyone. The Messenger of Allah (may Allah bless him and grant him peace) preferred, for what he needed to conceal of his needs, a mound or a palm-tree enclosure. So he entered one day into one of the enclosures of the Ansar, and there was a camel that came to him, and it made a gurgling sound, and its eyes shed tears—Bahz and ‘Affan said: When it saw the Prophet (may Allah bless him and grant him peace), it yearned and its eyes shed tears. The Messenger of Allah (may Allah bless him and grant him peace) wiped its hump and the back of its ears, so it calmed down. He then said: "Who is the owner of this camel?" A young man from the Ansar came and said: "It is mine, O Messenger of Allah." He said: "Do you not fear Allah regarding this beast which Allah has placed in your possession? For it has complained to me that you starve it and tire it out."