Maliks Muwatta Book 47, Hadith Number 10.

Section : Modesty.

Yahya related to me from Malik from Ibn Shihab from Salim ibn Abdullah from Abdullah ibn Umar that the Messenger of Allah, may Allah bless him and grant him peace, passed by a man who was chiding his brother about modesty. The Messenger of Allah, may Allah bless him and grant him peace, said, “Leave him. Modesty is part of iman.”