Evidence that the Adhaan is a Collective Obligation (Fard Kifaayah):
Anas (radiyallaahu `anhu) said: “The Messenger of Allaah (sallallaahu `alaihi wa sallam) used to attack the enemy when it was dawn. He would listen for the Adhaan; if he heard an Adhaan, he stopped, otherwise made an attack. Once on hearing a man say:
“Allaah is the Greatest, Allaah is the Greatest,” the Messenger of Allaah (sallallaahu `alaihi wa sallam) remarked:
“He is on the Fitrah (i.e., Islam).” Then upon hearing him say:
“I testify that there is none worthy of worship but Allaah, I testify that there is none worthy of worship but Allaah,” the Messenger of Allaah (sallallaahu `alaihi wa sallam) said:
“You have come out of the Fire (of Hell).” Then they looked and saw that he was a goatherd.”
Reported by Al-Bukhaaree (610) and Muslim (845).
