Musannaf Ibn Abi Shayba 3:3889

Affan narrated to us, he said: Hammam narrated to us, from Qatadah, from al-Hasan, from Samurah ibn Jundub, that the day of Hunayn was a rainy day. So the Prophet, peace and blessings of Allah be upon him, ordered his caller to announce: "The prayer is in the dwellings."