Musannaf Ibn Abi Shayba 3:5577

Waki’ narrated to us, he said: Mughirah ibn Ziyad al-Mawsili narrated to us, he said: I saw ‘Ata’ praying in the *Saqifah* (covered area) in the Sacred Mosque while traveling, while they were dispersing from the rows. So I said to him—or it was said to him—and he said: "I am an old man, and Makkah is behind me. The Messenger of Allah (peace and blessings of Allah be upon him) was on a journey, and rain afflicted him, so he led the people in prayer while they were in their dwellings, and Bilal would make the people hear the *Takbir*."