Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
tirmidhi:3644Saʿīd b. Yaʿqūb al-Ṭālqānī > Ayyūb b. Jābir > Simāk b. Ḥarb > Jābir b. Samurah

"The seal of the Messenger of Allah ﷺ" - meaning the one which was between his two shoulder blades - "was fleshy and red, resembling the egg of a pigeon."  

Abū ʿĪsá said that this Ḥadīth is Ḥasan-Ṣaḥīḥ.
الترمذي:٣٦٤٤حَدَّثَنَا سَعِيدُ بْنُ يَعْقُوبَ الطَّالْقَانِيُّ حَدَّثَنَا أَيُّوبُ بْنُ جَابِرٍ عَنْ سِمَاكِ بْنِ حَرْبٍ عَنْ جَابِرِ بْنِ سَمُرَةَ قَالَ

كَانَ خَاتَمُ رَسُولِ اللَّهِ ﷺ يَعْنِي الَّذِي بَيْنَ كَتِفَيْهِ غُدَّةً حَمْرَاءَ مِثْلَ بَيْضَةِ الْحَمَامَةِ  

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ