Musnad Ahmad 25:862

Ishaq narrated to us, Abd al-Rahman ibn Abi al-Zinad narrated to us, from Muhammad, from the family of Amr ibn Uthman, from Fatimah bint Husayn, she said: I heard Ibn Abbas saying: "The Messenger of Allah, may Allah bless him and grant him peace, forbade us from staring persistently at those afflicted with leprosy."