I heard Ka`b bin Malik talking after his failure to join (the Ghazwa of) Tabuk. He said, "When Igreeted Allah's Messenger (ﷺ) whose face was glittering with happiness, for whenever Allah's Messenger (ﷺ) washappy, his face used to glitter, as if it was a piece of the moon, and we used to recognize it (i.e. hishappiness) from his face."