I heard Kaʿb bin Malik talking after his failure to join (the Ghazwa of) Tabuk. He said, "When I greeted Messenger of Allah ﷺ whose face was glittering with happiness, for whenever Messenger of Allah 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."
فَلَمَّا سَلَّمْتُ عَلَى رَسُولِ اللَّهِ ﷺ وَهْوَ يَبْرُقُ وَجْهُهُ مِنَ السُّرُورِ وَكَانَ رَسُولُ اللَّهِ ﷺ إِذَا سُرَّ اسْتَنَارَ وَجْهُهُ حَتَّى كَأَنَّهُ قِطْعَةُ قَمَرٍ وَكُنَّا نَعْرِفُ ذَلِكَ مِنْهُ