Sunan Ibn Majah, 721

Rapporté par Sa’d bin Abu Waqqas : Le Messager d’Allah a dit : « Celui qui dit, en entendant le muezzin : “Wa ana Ash-hadu an la ilaha illallah wahdahu la sharika lahu, wa ash-hadu anna Muhammadan ‘abduhu wa rasuluhu, radaytu Billahi rabban wa bil-islami dinan wa bi muhammadin nabiyyan (Et je témoigne qu’il n’y a pas d’autre divinité qu’Allah seul, sans associé, et je témoigne que Muhammad est Son serviteur et Son Messager, et je suis satisfait qu’Allah soit mon Seigneur, l’islam ma religion et Muhammad mon Prophète),” ses péchés lui seront pardonnés. »

It was narrated from Sa'd bin Abu Waqqas that:The Messenger of Allah said: "Whoever says, when he hears the Mu'adh-dhin, 'Wa ana Ash-hadu an la ilaha illallah wahdahu la sharika lahu, wa ash-hadu anna Muhammadan 'abduhu wa rasuluhu, radaytu Billahi rabban wa bil-islami dinan wa bi muhammadin nabiyyan (And I bear witness that none has the right to be worshipped but Allah alone, with no partner, and I bear witness that Muhammad is His slave and Messenger, and I am content with Allah as my Lord, Islam as my religion and Muhammad as my Prophet),' his sins will be forgiven to him