THE BUDDHA SHINES THROUGHOUT DAY AND NIGHT
Diva tapati adicco rattim abhati candima
Sannaddho khattiyo tapati jhayi tapati brahmano
Atha sabbam ahorattim Buddho tapati tejasa.
By day shines the sun; by night shines the moon; in regalia shines the king;
in meditation shines the Arahant; but the Buddha in his glory shines at all times, by day and by night. 
It was the full moon day of the seventh month when King Pasenadi of Kosala came to visit the Buddha. The king was then resplendent in his full royal regalia. At that time, Venerable Kaludayi was also present in the same room, sitting at the edge of the congregation. He was in deep mental absorption(Jhana), and his body became bright and golden. In the sky, the Venerable Ananda noticed that the sun was setting and the moon was just coming out, with both the sun and the moon radiating rays of light.
When Ananda looked at the Buddha, he suddenly perceived that the light that was then radiating from the Buddha far surpassed the light shining from the others. Seeing the Buddha in his glory and splendour, Ananda immediately exclaimed, 'O, Venerable Sir! The light that shines forth from your noble body far surpasses the light from the king, the light from Venerable Kaludayi, and the light from the sun and the moon.' The Buddha replied, 'All Buddhas shine both by night and by day, and shine with fivefold brightness.*
- By attaining Sainthood.
*The Buddha eclipses immorality by the power of morality(sila), vice by the power of virtue(guna), ignorance by the power of wisdom(panna), demerit by the power of merit(punna), unrighteousness by the power of righteousness(dhamma).