Jabir bin Samura reported,

I saw a seal on the back of the Messenger of Allah ﷺ, like a pigeon's egg.

Muslim 6086

Sahih

وحدثنا ابن نمير حدثنا عبيد الله بن موسى أخبرنا حسن بن صالح عن سماك بهذا الإسناد مثله

مسلم 6086صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Virtues
Chapter
Affirmation of the seal of prophethood, its description, and its location on his body ﷺ
Numbering
Darussalam 6086
Muslim 6086