Musnad Ahmad 33:1054

I read to Abd al-Rahman: Malik, and it was narrated to us by Ishaq, who informed us from Malik, from Ja'far, from his father, from Jabir ibn Abdullah: That the Messenger of Allah (peace and blessings of Allah be upon him), when he stood upon al-Safa, would say the takbir three times, and say: "There is no god but Allah alone, He has no partner; to Him belongs the dominion, and to Him belongs the praise, and He is capable of all things." And in the hadith of Abd al-Rahman: He would do that three times, and supplicate, and he would do the same upon al-Marwa.