Musnad Ahmad 289:6

Yazid ibn Harun narrated to us, he said: Hammad ibn Salamah informed us, from Ya'la ibn 'Ata, from Waki' ibn 'Udas, from his paternal uncle Abu Razin, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Our Lord laughs at the despair of His servant and the nearness of his relief." I said: "O Messenger of Allah, does the Lord, Mighty and Majestic is He, laugh?" He said: "Yes." He said: "We shall never be deprived of good from a Lord who laughs."