The Buddha explains the fruit, benefit, brightness, and reach of observing the Uposatha endowed with the eight factors in detail.

Vitthatūposatha sutta - Uposatha In Detail

"Bhikkhus, when the Uposatha is observed, endowed with the eight factors, it is of great fruit, of great benefit, superbly bright, and far-reaching. And how, bhikkhus, is the Uposatha observed, endowed with the eight factors, of great fruit, of great benefit, superbly bright, and far-reaching?"

1 Here, bhikkhus, a disciple of the noble ones reflects thus: 'For as long as they live, the arahants, having abandoned the taking of life, refrain from taking life, having laid aside weapons and sticks, are conscientious, full of kindness, and dwell with compassion for the well-being of all breathing beings. Today, for this night and day, I too, having abandoned the taking of life, will refrain from taking life, have laid aside weapons and sticks, will be conscientious, full of kindness, and dwell with compassion for the well-being of all breathing beings. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the first factor.

2 'For as long as they live, the arahants, having abandoned the taking of what is not given, refrain from taking what is not given, accept what is given, and expect only what is given. They dwell with a pure, blameless mind. Today, for this night and day, I too, having abandoned the taking of what is not given, will refrain from taking what is not given, will accept what is given, and expect only what is given. I will dwell with a pure, blameless mind. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the second factor.

3 'For as long as they live, the arahants, having abandoned unchastity, are celibate, far-removed from sensuality, and refrain from sexual activity, the common person's practice. Today, for this night and day, I too, having abandoned unchastity, will be celibate, far-removed from sensuality, and will refrain from sexual activity, the common person's practice. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the third factor.

4 'For as long as they live, the arahants, having abandoned false speech, refrain from false speech, are truthful, are connected with truth, stable, dependable, and do not deceive the world. Today, for this night and day, I too, having abandoned false speech, will refrain from false speech, will be truthful, will be connected with truth, will be stable, will be dependable, and will not deceive the world. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the fourth factor.

5 'For as long as they live, the arahants, having abandoned spirits, alcoholic beverages, drugs and states of negligence, refrain from intoxicants that cause negligence. Today, for this night and day, I too, having abandoned wine, spirits, drugs and states of negligence, will refrain from intoxicants that cause negligence. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the fifth factor.

6 'For as long as they live, the arahants, having become ones who eat only one meal a day, abstain from eating at night, refraining from untimely eating. Today, for this night and day, I too, having become one who eats only one meal a day, will abstain from eating at night, and will refrain from untimely eating. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the sixth factor.

7 'For as long as they live, the arahants, having abandoned dancing, singing, music, and watching shows, as well as wearing garlands, using perfumes, oils, and beautifying the body with ornaments, refrain from these activities. Today, for this night and day, I too, having abandoned dancing, singing, music, and watching shows, as well as wearing garlands, using perfumes, oils, and beautifying the body with ornaments, will refrain from these activities. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the seventh factor.

8 'For as long as they live, the arahants, having abandoned high and luxurious beds, refrain from high and luxurious beds and make use of low beds, whether a simple cot or a spread of grass. Today, for this night and day, I too, having abandoned high and luxurious beds, will refrain from high and luxurious beds and will make use of a low bed, whether a simple cot or a spread of grass. In this way, I shall follow the example of the arahants, and the Uposatha will be observed by me.' Thus, one is endowed with the eighth factor. Thus observed, bhikkhus, the Uposatha endowed with the eight factors is of great fruit, of great benefit, superbly bright, and far-reaching.

How great is its fruit? How great is its benefit? How superbly bright and far-reaching is it? Suppose, bhikkhus, someone were to rule over the sixteen great regions, possessing abundant wealth and royal treasures, such as, the regions of the Aṅgas, Magadhas, Kāsīs, Kosalas, Vajjians, Mallans, Cetis, Vaṅgas, Kurus, Pañcālas, Macchas, Sūrasenas, Assakas, Avantis, Gandhāras, and Kambojas—this would not be worth a sixteenth part of the fruit and benefit of the Uposatha endowed with the eight factors. For what reason? Because, bhikkhus, human kingship is insignificant compared to divine happiness.

Bhikkhus, fifty human years equal one day and night for the deities of the Four Great Kings. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the devas of the Four Great Kings is five hundred celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the devas of the Four Great Kings. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Bhikkhus, one hundred human years equal one day and night for the gods of the Thirty-Three. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the gods of the Thirty-Three is one thousand celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the gods of the Thirty-Three. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Bhikkhus, two hundred human years equal one day and night for the Yāma gods. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the Yāma gods is two thousand celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the Yāma gods. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Bhikkhus, four hundred human years equal one day and night for the Tusita gods. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the Tusita gods is four thousand celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the Tusita gods. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Bhikkhus, eight hundred human years equal one day and night for the Nimmānarati gods. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the Nimmānarati gods is eight thousand celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the Nimmānarati gods. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Bhikkhus, sixteen hundred human years equal one day and night for the Paranimmita-vasavatti gods. Thirty such days make a month, and twelve months make a year. By that reckoning, the lifespan of the Paranimmita-vasavatti gods is sixteen thousand celestial years. It is indeed possible, bhikkhus, that here some woman or man, having observed the Uposatha endowed with the eight factors, upon the breaking up of the body after death, might be reborn in the company of the Paranimmita-vasavatti gods. It is with reference to this, bhikkhus, that I said human kingship is insignificant compared to divine happiness.

Verse

One should not harm living beings or take what is not given, One should not speak falsehood or indulge in intoxicants; One should refrain from sexual activity or engage in unchastity, One should not eat at night or partake in untimely eating.
One should not wear garlands or apply perfumes, One should rest on a low bed or on the ground; This is the eightfold Uposatha observance, declared by the Buddha, who reached the end of suffering.
The moon and the sun, both beautiful to behold, travel shining as far as their light reaches; Dispellers of darkness, moving in the sky, shining and illuminating the directions.
Whatever wealth is found in the world, pearls, gems, and excellent beryl; Ornamental gold, refined gold, and the natural gold called haṭaka.
Compared to the Uposatha endowed with the eight factors, the wealth of the world is not worth a sixteenth part; Just as all the hosts of stars cannot rival the moonlight.
Therefore, a virtuous woman or man, observing the Uposatha endowed with the eight factors; Having performed merit that leads to happiness, through blamelessness, attains the heavenly state.