Do you think that you could enter paradise unless God takes cognizance of your having striven hard [in His cause], and takes cognizance of your having been patient in adversity?
Al-Imran (The Family of Imran) Verse 142
Allah's Apostle said, "Whenever you hear the Adhan, say what the Mu'adhdhin is saying.
Sahih Bukhari: Volume 1, Book 11, Number 585