Musnad Ahmad 1153:1252

Abu Ahmad narrated to us, Sufyan narrated to us, from Usamah, from Uthman ibn Urwah, from Urwah, from Aisha, she said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Indeed, Allah, the Almighty and Majestic, and His angels send blessings upon those who join the rows."