Two Arabis came to the Prophet ﷺ, and one of them asked, "Muhammad, who is the best of men?"The Prophet ﷺ replied, "He whose life is long and whose deeds are good."The other said, "The laws of Islam have become many for us, so give us something comprehensive to hold fast to."He answered, "Let your tongue remain moist with the remembrance of Allah."
أتى النبي ﷺ أعرابيان، فقال أحدهما: من خير الرجال يا محمد؟ قال النبي ﷺ: من طال عمره وحسن عمله. وقال الآخر: إن شرائع الإسلام قد كثرت علينا، فباب تمسك به جامع؟ قال: لا يزال لسانك رطبا من ذكر الله.
Narrated by Tirmidhi (2329, 3375) and Ahmad (17680, 17698), and this wording is his, both of them through routes from Amr bin Qays Kindi, from Abdullah bin Busr, who related it. Its isnad is sahih. Hakim said, "This is a hadith with a sahih isnad."