Jami` at-Tirmidhi, Volume 6, Book 46, Hadith 3637 (DarusSalam) ⓘ

Narrated 'Ali: "The Prophet 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."

حَدَّثَنَا مُحَمَّدُ بْنُ إِسْمَاعِيلَ، حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا الْمَسْعُودِيُّ، عَنْ عُثْمَانَ بْنِ مُسْلِمِ بْنِ هُرْمُزَ، عَنْ نَافِعِ بْنِ جُبَيْرِ بْنِ مُطْعِمٍ، عَنْ عَلِيٍّ، قَالَ لَمْ يَكُنْ رَسُولُ اللَّهِ صلى الله عليه وسلم بِالطَّوِيلِ وَلاَ بِالْقَصِيرِ شَثْنَ الْكَفَّيْنِ وَالْقَدَمَيْنِ ضَخْمَ الرَّأْسِ ضَخْمَ الْكَرَادِيسِ طَوِيلَ الْمَسْرُبَةِ إِذَا مَشَى تَكَفَّأَ تَكَفُّؤًا كَأَنَّمَا انْحَطَّ مِنْ صَبَبٍ لَمْ أَرَ قَبْلَهُ وَلاَ بَعْدَهُ مِثْلَهُ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ ‏.‏