Volume 1, Book 11, Number 577:
Narrated Anas:
The people mentioned the fire and the bell (they suggested those as signals to indicate the starting
of prayers), and by that they mentioned the Jews and the Christians. Then Bilal was ordered to pro –
nounce Adhan for the prayer by saying its wordings twice, and for the Iqama (the call for the actual
standing for the prayers in rows) by saying its wordings once. (Iqama is pronounced when the
people are ready for the prayer).