Musannaf Ibn Abi Shayba 33:827

Zayd ibn al-Hubab narrated to us, he said: Mu'awiyah ibn Salih narrated to us, he said: 'Abd al-Rahman ibn Jubayr ibn Nufayr narrated to me, from his father, from Abu al-Darda', that he said: Those whose tongues remain moist with the remembrance of Allah will enter Paradise while they are laughing.