Mukhtasar Muslim (Abridged) 200 — Virtue of one who repeats adhan like

The conqueror of Persia, Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him), narrates from the Noble Prophet (peace and blessings be upon him) that he (peace be upon him) said: Whoever, upon hearing the call of the muezzin, says: I bear witness that there is no deity except Allah, He is One and has no partner, and Muhammad (peace and blessings be upon him) is Allah's servant and Messenger. I am pleased and content with Allah's Lordship, with Muhammad's (peace and blessings be upon him) Messengership, and I have accepted the religion of Islam—then the sins of such a person are forgiven.