Musnad Abu Ya'la al-Mawsili 70:1

Harun ibn Ma'ruf narrated to us, Abdullah ibn Wahb narrated to us, Amr informed me that Sulayman ibn Ziyad al-Hadrami narrated to him that Abdullah ibn al-Harith ibn Juz' al-Zubaydi narrated to him: That he and a companion of his passed by Umm Ayman and some youths from Quraysh who had loosened their waist-wrappers and made them into whips, striking one another with them while they were naked. Abdullah said: When we passed by them, they said, "These are monks, so leave them alone." Then the Messenger of Allah (peace be upon him) came out to them. When they saw him, they scattered. The Messenger of Allah (peace be upon him) returned in anger until he entered [his dwelling]. I was behind the chamber and I heard him saying, "Glory be to Allah! They were neither ashamed before Allah, nor did they cover themselves from His Messenger." Umm Ayman was with him, saying, "Ask forgiveness for them, O Messenger of Allah." Abdullah said: By my father, he did not ask forgiveness for them.