Musannaf Ibn Abi Shayba 21:339

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