Musnad Ahmad 30:1202

Al-Aswad ibn Amir narrated to us, Kamil informed us, from Abu Salih, from Abu Hurairah, who said: It was said to the Messenger of Allah, peace and blessings of Allah be upon him: "Do you not feel protective jealousy?" He said: "By Allah, I do feel protective jealousy, and Allah is more protective than I am. And out of His protective jealousy, He has forbidden immoralities."