Sunan Abi Dawud Book 35, Hadith 31
When I parted the hair of the Messenger of Allah (ﷺ) I made a parting from the crow of his head and let his forelock hang between his eyes.
The people of the Book used to let their hair hand down, and the polytheists used to part their hair. The Messenger of Allah (ﷺ) like to confirm with the People of the Book in the matters about which he had received no command. Hence he Messenger of Allah (ﷺ) let his forelock hang down but afterwards he parted it.
I came to the Prophet (ﷺ) and I had long hair. When the Messenger of Allah (ﷺ) saw me, he said: Evil, evil! He said: I then returned and cut them off. I then came to him in the morning. He said (to me): I did not intend to do evil to you. This is much better.