Musnad Abu Ya'la al-Mawsili 42:183

Abu Khaythama narrated to us, Abd al-Rahman narrated to us, from Shu'bah, from Qatadah, who said: I heard Abdullah ibn Abi Utbah saying: I heard Abu Sa'id saying: The Messenger of Allah (peace and blessings of Allah be upon him) was more bashful than a virgin in her private quarters. And if he disliked something, we would recognize it in his face.