Musnad Ahmad 8:164

Surayj ibn al-Nu‘man narrated to us, Abu Shihab narrated to us, from al-Hajjaj, from Ibn Abi Najih, from Mujahid, from Sa‘d ibn Malik, who said: We performed tawaf with the Messenger of Allah, may Allah bless him and grant him peace. Some of us performed tawaf seven times, some of us performed tawaf eight times, and some of us performed tawaf more than that. The Messenger of Allah, may Allah bless him and grant him peace, said: "There is no harm."