Jami` at-Tirmidhi 3637

Narrated 'Ali:"The Prophet (ﷺ) was not tall nor was he short, his hands and feet were thick, his head was large, he was big-boned, he had a long Masrubah (the line of hair from the chest to the navel), and whenever he walked, he leaned forward as if he was going down a decline. I have not seen anyone before him nor after him that resembled him (ﷺ)