once the Holy Prophet Muhammad (S) sent a group of people with the orders that,
“At such and such time of the night you shall loose your way, then go towards the left and you shall meet a man, who will be having a herd of Sheep. You ask him the way, but he shall not show you the way until you eat with him. Then he will sacrifice a sheep and prepare food for you and eat along with you, then he will show you the way. You convey my greetings to him and inform him about my appearance in Madina.”
They left, and as predicted lost their way. One of them said, “Did not the Prophet tell us to go to the left side”? They went towards the left and met the man, regarding whom the Prophet had prophesied, and asked him the way. The man being none other than ‘Amr bin Humaq, who asked them, “Has the Prophet appeared in Madina”? They replied in the affirmative and he accompanied them. He went to the presence of the Holy Prophet (S) and remained there until Allah willed, then the Prophet told him,
“Return to the place where you have come from, when the Commander of the faithful Ali becomes in charge of Kufa, go to him.”
‘Amr returned back until the time Imam Ali (a.s.) became the Caliph in Kufa, and he came to him and resided there.
Reference : Nafasul Mahmoom – Shaikh abbas Qummi (r.a.)