It is narrated from the Prophet صلى الله عليه وعلى آله وسلم that He صلى الله عليه وعلى آله وسلم performed Tawaf, exited the mosque, and began at al-Ṣafa, saying: "Begin with what Allah سبحانه وتعالى began with."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 100