Mustadrak al-Hakim — Hadith 7558

Qays bin Bishr al-Taghlibi says: My father used to sit with Sayyiduna Abu al-Darda' (may Allah be pleased with him) in Damascus. In Damascus there was a man of the Ansar from among the Companions of the Messenger of Allah (peace and blessings be upon him) who was called Ibn al-Hanzaliyyah. He kept to himself and rarely sat with people; he was occupied in prayer, and when he finished, he would be busy with takbir, tasbih and tahlil until he reached his home. One day he passed by us while we were with Sayyiduna Abu al-Darda' (may Allah be pleased with him), and he greeted us with salam. Sayyiduna Abu al-Darda' (may Allah be pleased with him) said: "Tell us something that will benefit us and will not harm you." He said that the Messenger of Allah (peace and blessings be upon him) said: "You are about to arrive among your brothers, so make your clothing proper and put your saddles and belongings in order, until you stand out among people like a beauty mark. Indeed, Allah Almighty does not love obscenity and foul speech."
This hadith is sahih al-isnad (its chain is authentic), but the two Shaykhs (Bukhari and Muslim) did not record it. And Ibn al-Hanzaliyyah, whom the narrator did not name, is Sayyiduna Sahl bin al-Hanzaliyyah (may Allah be pleased with him), one of the ascetics among the noble Companions.