Numerous corroborating reports to this effect have come from ʿAlī, and something similar is related from ʿUmar as well.

Al-Wāqidī said:
Bukayr ibn Mismar narrated to us, from Ziyād, the freedman of Saʿd, who said:
“I asked Saʿd ibn Abī Waqqāṣ, ‘Did the Messenger of Allah ever dye his hair?’
He replied, ‘No—and he never even contemplated doing so. The few gray hairs he had were in his goatee and in the front of his head; if I wished, I could have counted them.’
I then asked, ‘How would you describe him?’
He answered, ‘He was a man neither tall nor short, neither chalk-white nor dark-brown; his hair was neither limp nor tightly curled. His beard was fine, his forehead smooth and radiant, tinged with a rosy hue. His fingers were thick, and the hair of his head and beard was a deep jet-black (1).’

Al-Ḥāfiẓ Abū Nuʿaym al-Iṣfahānī said:
ʿAbd Allāh ibn Jaʿfar ibn Aḥmad ibn Fāris narrated to us; Yaḥyā ibn Ḥātim al-ʿAskarī narrated to us; Basr ibn Mihrān narrated to us; Shurayk narrated to us, from ʿUthmān ibn al-Mughīrah, from Zayd ibn Wahb, from ʿAbd Allāh ibn Masʿūd, who said:
“The very first thing I learned about the Messenger of Allah occurred when I came to Mecca with several of my uncles. They directed us to al-ʿAbbās ibn ʿAbd al-Muṭṭalib, and we found him seated by Zamzam, so we sat with him. While we were with him, a man approached from the Ṣafā Gate: fair-skinned with a rosy glow, his wavy locks falling halfway down his ears, aquiline-nosed, with gleaming incisors, large dark eyes, a full beard, a thin line of hair down his chest, and broad hands and feet. He wore two white garments and looked like the full moon on a cloudless night.

He (Abū Nuʿaym) went on to recount the rest of the report—his circumambulation of the House, his prayer there with Khadījah and ʿAlī ibn Abī Ṭālib—and that they asked al-ʿAbbās about him. He said, ‘This is my nephew Muḥammad ibn ʿAbd Allāh; he claims that God has sent him to all people’ (2).

It is authentically recorded in both Ṣaḥīḥs, on the authority of Anas, that the Messenger of Allah ﷺ said: ‘Indeed, I see you from behind my back’ (3).

Some scholars explained that he meant this with the eye of his heart, and some even interpreted the verse, ‘And your turning among those who prostrate’ (al-Shuʿarāʾ 219) accordingly—but that explanation is weak.

Others maintained that this was one of his unique miracles ﷺ: he could see with his physical eyesight what was behind him just as he saw what was before him. Al-Ḥāfiẓ Abū Zurʿah al-Rāzī stated this explicitly in his book Proofs of Prophethood, devoting a chapter to it and citing the related ḥadīths through sound chains—from Ḥumayd, ʿAbd al-ʿAzīz ibn Ṣuhayb, and Qatādah, all from Anas—thereby recording them.