Silsilat al-Ahadith al-Sahihah

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: A healer from the tribe of Banu Amir came to the Messenger of Allah (peace and blessings be upon him) and said: O Muhammad! You say strange and wondrous things, so may I treat you? The Messenger of Allah (peace and blessings be upon him) invited him towards Allah the Exalted and said: "Shall I show you a (special) sign?" There were date palms and other trees near you. The Messenger of Allah (peace and blessings be upon him) called a cluster of dates, and it turned towards you, prostrating and raising its head as it came to you, and stood before you. Then the Messenger of Allah (peace and blessings be upon him) said: "Return to your place." It returned. Seeing this sign, the man from Amir said: By Allah! I will never deny you. Then he said: O family of Banu Sa'sa'ah! Whatever you (peace and blessings be upon him) say, I will never deny you.