Bukhari Vol. 6 : No. 13 (Hadith)

Narrated Al-Bara (Radi-Allahu 'anhu):

The Prophet (Sallallahu 'Alaihi Wa Sallam) prayed facing Bait-ul-Maqdis
(i.e. Jerusalem) for sixteen or seventeen months but he wished that his
Qibla would be the Ka'ba (at Makkah). So Allah Revealed (2.144) and he
offered 'Asr prayers (in his Mosque facing Ka'ba at Makkah) and some people
prayed with him. A man from among those who had prayed with him, went out
and passed by some people offering prayer in another mosque, and they were
in the state of bowing. He said, "I, (swearing by Allah) testify that I
have prayed with the Prophet facing Makkah." Hearing that, they turned
their faces to the Ka'ba while they were still bowing. Some men had died
before the Qibla was changed towards the Ka'ba. They had been killed and we

did not know what to say about them (i.e. whether their prayers towards
Jerusalem were accepted or not). So Allah revealed: "And Allah would never
make your faith (i.e. prayer) to be lost (i.e. your prayers offered
(towards Jerusalem). Truly Allah is Full of Pity, Most Merciful towards
mankind." (2.143)