Narrated Al−Bara' (bin `Azib): When the Prophet came to
Medina, he stayed first with his grandfathers or maternal uncles from Ansar. He offered his prayers facing Baitul−Maqdis (Jerusalem) for sixteen or seventeen months, but he wished that he could pray facing the Ka`ba (at Mecca).
The first prayer which he offered facing the Ka`ba was the `Asr prayer in the company of some people. Then one of those who had offered that prayer with him came out and passed by some people in a mosque who were bowing during their prayers (facing Jerusalem). He said addressing them, "By Allah, I testify that I have prayed with Allah's Apostle facing Mecca (Ka`ba).' Hearing that, those people changed their direction towards the Ka`ba immediately. Jews and the people of the scriptures used to be pleased to see the Prophet facing Jerusalem in prayers but when he changed his direction towards the Ka`ba, during the prayers, they disapproved of it. Al−Bara' added, "Before we changed our direction towards the Ka`ba (Mecca) in prayers, some Muslims had died or had been killed and we did not know what to say about them (regarding their prayers.) Allah then revealed: And Allah would never make your faith (prayers) to be lost (i.e. the prayers of those Muslims were valid).' " (2:143).