Musnad Ahmad Hadith 23805

It is narrated from Abu Tufail (may Allah be pleased with him) that during the Prophetic era, a child was born to a man. That person brought his child to the service of the Noble Prophet (ﷺ). The Noble Prophet (ﷺ) passed his hand over the child's forehead and prayed for blessings for him. Consequently, a hair grew on the child's forehead like a bow. That boy grew up, and when the time of the Khawarij came, he began to have affection for the Khawarij. As a result of this misfortune, the hair on his forehead fell out. His father caught him and shackled his feet so that he would not join the Khawarij. One day, we went to him and advised him, and among many things, we also said to him, "Do you not see that the blessing of the Noble Prophet's (ﷺ) prayer has vanished from your forehead?" We kept advising him until he abandoned their opinion, and after some time, Allah caused that hair to grow again on his forehead, and he repented.