Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) said that when the Messenger of Allah (peace and blessings be upon him) stood upon Safa, he would say the takbir three times and say: "La ilaha illallahu wahdahu la sharika lah, lahu al-mulku wa lahu al-hamd, wa huwa 'ala kulli shay'in qadir" (There is no god worthy of worship except Allah, alone, without partner; to Him belongs the dominion and to Him belongs all praise, and He has power over all things). He would say this three times and supplicate, and on Marwah too he would do the same three times.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9335