Musannaf Ibn Abi Shaybah

Ibrahim says that when you touch the Black Stone, say: "There is no god but Allah, and Allah is the Greatest."

When Hazrat Umar would touch the Black Stone, he would say: "I believe in Allah and I disbelieve in false gods."

When Hazrat Ali (may Allah be pleased with him) would perform the Istilam of the Black Stone, he would recite this supplication: O Allah! I affirm and follow Your Book and the Sunnah of Your Prophet.

It is narrated in a similar manner from Hazrat Ali (may Allah be pleased with him).

Hazrat Ata says that when you perform Istilam of Hajar Aswad, kiss your hands and do not make a sound while kissing.