Safiyyah bint Majza'ah narrates that Abu Mahdhurah (may Allah be pleased with him) had a lock of hair on the front part of his head; when he sat down he would let it loose and it would reach the ground. People said to him: "Why do you not shave it off?" He said: "The Messenger of Allah (peace and blessings be upon him) passed his blessed hand over it, so I will not shave it off until I die." And indeed he did not shave it off until he died.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6716