(23) باب صِفَةِ النَّبِيِّ صلى الله عليه وسلم
Narrated `Abdullah bin Ka`b:
I heard Ka`b bin Malik talking after his failure to join (the Ghazwa of) Tabuk. He said, "When I greeted Allah's Messenger (ﷺ) whose face was glittering with happiness, for whenever Allah's Messenger (ﷺ) was happy, his face used to glitter, as if it was a piece of the moon, and we used to recognize it (i.e. his happiness) from his face."
Reference: Sahih al-Bukhari 3556
In-book reference: Book 61, Hadith 65
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 56, Hadith 756