Musnad Ahmad 27:734

Yahya ibn Sa'id narrated to us, Malik narrated to us, al-Zuhri narrated to us, from Salim, from his father, that a man from the Ansar was admonishing his brother regarding shyness (haya'). The Prophet, peace and blessings of Allah be upon him, said: "Leave him, for indeed shyness is from faith."