Sayyiduna Abdullah bin Busr (may Allah be pleased with him) narrates that two Bedouins came to him (peace and blessings be upon him) and asked questions. One of them said: O Messenger of Allah, which people are best? He (peace and blessings be upon him) said: "The one whose life is long and whose deeds are righteous." Then the other said: O Messenger of Allah, the laws (branches) of Islam are many; tell me of one deed that I can hold fast to. He (peace and blessings be upon him) said: "Let your tongue always remain moist with the remembrance of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6526