Maliks Muwatta Book 20, Hadith Number 128.
Section : Starting with Safa in the Say.
Yahya related to me from Malik from Jafar ibn Muhammad ibn Ali from his father from Jabir ibn Abdullah that the Messenger of Allah, may Allah bless him and grant him peace, used to say, “Allah is greater” three times when he stopped on Safa, and “There is no god but Allah, alone, without any partner. To Him belong the Kingdom and praise, and He has power over everything” three times, and make dua. He would then do the same on Marwa.