'Abdullah bin Busr (May Allah be pleased with him) reported:
One of the Companions said, "O Messenger of Allah. There are many injunctions of Islam for me. So tell me something to which I may hold fast." He said, "Keep your tongue wet with the remembrance of Allah."[At-Tirmidhi]. (ES)
App reference (ES): Book 16, Hadith 31 (ES)
Arabic/English book reference (ES): Book 16, Hadith 1438 (ES)