The great reward for calling out the azaan

عن عبد الله بن عمرو رضي الله عنهما قال قال رسول الله صلى الله عليه وسلم المؤذن المحتسب كالشهيد المتشحط في دمه إذا مات لم يدود في قبره (الترغيب والترهيب 1/250)

Hazrat Abdullah ibn Amr (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said: “The muazzin who calls out the azaan with the hope of attaining reward is like the martyr soiled with the blood (of martyrdom), who upon passing away, is protected from the worms in his grave.”