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 Apostle whose face was glittering with happiness, for whenever Allah's Apostle 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."

حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، عَنْ عُقَيْلٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَبْدِ اللَّهِ بْنِ كَعْبٍ، أَنَّ عَبْدَ اللَّهِ بْنَ كَعْبٍ، قَالَ سَمِعْتُ كَعْبَ بْنَ مَالِكٍ، يُحَدِّثُ حِينَ تَخَلَّفَ عَنْ تَبُوكَ، قَالَ 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.