Volume 4, Book 52, Number 235:
Narrated Abu Musa Al-Ashari:
We were in the company of Allah’s Apostle (during Hajj). Whenever we went up a high place we
used to say: “None has the right to be worshipped but Allah, and Allah is Greater,” and our voices
used to rise, so the Prophet said, “O people! Be merciful to yourselves (i.e. don’t raise your voice), for
you are not calling a deaf or an absent one, but One Who is with you, no doubt He is All-Hearer,
ever Near (to all things).”