It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that whenever the Prophet (peace and blessings be upon him) stood on the hill of Safa or Marwah, he would say "Allahu Akbar" three times and then recite these words: "There is no deity except Allah, He is alone, He has no partner, sovereignty belongs to Him and all praise is for Him, and He has power over everything." In another chain of narration, it is also mentioned that after doing this three times, the Prophet (peace and blessings be upon him) would supplicate, and he would repeat the same on Marwah as well.