The Hadith of Holy Prophet (sallal laahu alaihi wasallam) says that if a man recites the above mentioned Durood Shareef 7 times, for 7 Fridays, then the mercy of Sayyiduna Rasoolullah (sallal laahu alaihi wasallam) will reach him. (The name “Da’im” means “permanent”. Thus, this Durood Shareef should be recited by every Muslim permanently).