Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 139
Narrated 'Abdullah bin 'Umar:
The Prophet passed by a man who was admonishing his brother regarding Haya and was saying, "You are very shy, and I am afraid that might harm you." On that, Allah's Apostle said, "Leave him, for Haya is (a part) of Faith."