Musnad Ahmad 1156:65

Sayyar narrated to us, he said: Ja'far—meaning Ibn Sulayman—narrated to us, he said: Al-Mughirah ibn Habib, the son-in-law of Malik ibn Dinar, narrated to us, he said: A sheikh from the people of Medina narrated to me, from Umm Salamah, she said: The Messenger of Allah (peace and blessings of Allah be upon him) said to me: "Prepare the sitting place for us, for an angel is descending to the earth who has never descended to it before."