Musnad Abu Ya'la al-Mawsili 110:23

Ibrahim ibn al-Hajjaj narrated to us, Abd al-Wahid ibn Ziyad narrated to us, Sulayman al-A'mash narrated to us, from Salim ibn Abi al-Ja'd, from Ibn Abbas, who said: A man from Banu 'Amir came to the Prophet, may Allah bless him and grant him peace, who used to practice medicine and healing. He said to him, "O Muhammad, you say things; would you like me to heal you?" The Messenger of Allah, may Allah bless him and grant him peace, called him, then said to him, "Would you like me to show you a sign?" There were palm trees and trees near him. He said, "Yes." The Messenger of Allah, may Allah bless him and grant him peace, called a cluster of dates from it. It came toward him while it was prostrating, raising and lowering its head, until it reached him and stood before him. Then the Messenger of Allah, may Allah bless him and grant him peace, said to it, "Return to your place," and it returned to its place. He said, "By Allah, I will never call you a liar regarding anything you say after this, ever." Then he said, "O 'Amir ibn Sa'sa'ah, by Allah, I will never call him a liar regarding anything he says after this, ever." He said: The *'adhq* (cluster) is the palm tree.