Authentic Supplication Number 3.
Abdullah bin Busr recounted that a man said: “O’ Messenger of Allah! The teachings of the faith have become many upon me, so tell me of something which I can adhere to.” He said: “That your tongue remain moist with the remembrance of Allah, The Exalted.”
Reported by At-Tirmithi, and he said it was somely (hasan). Al-Albani said this was an under-rating because it is really sound (saheeh), that so said Al-Hakim, and that Ath-Thahabi agreed with Al-Hakim. Al-Albani included this hadeeth in The Authentic of Good Sayings as #3.