I have come along several questions of the kind on this site to repeat a certain phrase several times and get reward or forgiveness.
As what I have read and been taught, God promises reward to the faithful who do good deeds and forgiveness through repentance, possible compensation and asking for forgiveness.
There are Hadith that the Prophet (p.b.u.h) repeated different things 3 times (but not for any reward), and I found similar once but not going back to the Prophet and without a specified reward.
Where does the teaching to repeat words to achieve this come from? Is it considered a valid repentance?