The caliph al-Mahdi entered the Masjid of the Messenger of Allah (peace and blessings of Allah be upon him) and the people all stood up for him except Imam Ibn Abi Dhi’b.

It was said to him: "Stand up; this is the Ameer al-Mu’mineen."

He said: "The people should only stand up for the Lord of the Worlds."

Al-Mahdi said: "Let him be, for all the hairs of my head have stood on end."

 
[Siyar A’laam al-Nubala’ (7/144).]