Musnad Abu Ya'la al-Mawsili 140:23

Ibrahim ibn al-Hajjaj al-Nayli narrated to us, Salih narrated to us, from Thabit, Yazid al-Raqashi, and Maymun ibn Siyah, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "O people, indeed your Lord is Shy and Generous; He is shy that one of you should raise his hands to Him, and He returns them empty."