Musnad Ahmad 534:25

'Abd al-Rahman ibn Mahdi narrated to us, from Mu'awiyah—meaning Ibn Salih—from 'Amr ibn Qays, who said: I heard 'Abdullah ibn Busr saying: Two Bedouins came to the Messenger of Allah, may Allah bless him and grant him peace. One of them said: "O Messenger of Allah, which of the people is best?" He said: "He whose life is long and whose deeds are good." The other said: "O Messenger of Allah, the laws of Islam have become too many for me, so command me with a matter that I may hold fast to." He said: "Let your tongue remain moist with the remembrance of Allah."