Srimad Bhagvata Mahapurana: Book 8: Chapter 18: Verses 1-14
The Lord appears as the divine Dwarf and visits the sacrificial performance of Bali
Sri Suka resumed : The Lord, whose exploits and glory were thus celebrated by Brahma (the creator) and who is the Fountain-head of immortality (final beatitude), took His descent from Aditi. He was endowed with four arms-in which He carried a conch, a mace, a lotus and a discus-was clad in yellow and had eyes big as a pair of lotuses. Bright dark-brown of hue, the supreme Person bore the mark of Srivatsa (a white curl of hair) on His bosom. The lustre of His lotus countenance was augmented by the brilliance of His alligator-shaped ear-rings; and a diadem, girdle strings and a charming pair of anklets shone (on His person) along with a pair each of wristlets and armlets. Adorned with His (characteristic and) splendid wreath of sylvan flowers deeply resonant with the humming of swarms of black bees and with the (celebrated) Kaustubha gem suspended from His neck, Sri Hari dispersed the gloom of the house of Kasyapa (a lord of created beings) by His own radiance. At that time the quarters brightened up and the lakes and ponds etc., became clear, created beings felt much delighted, and (all the six) seasons exhibited their (own) characteristics (in the shape of fruits and flowers of every description). Heaven, earth and the aerial region, the gods (having the flames of fire for their tongues), the cows and the Brahmanas as well as mountains were transported with joy.
The Lord appeared on the Sravana-Dwadasi (the twelfth day of the bright half of Bhadrapada) when the moon happened to be in the mansion called Srona (Sravana) and in an hour known by the name of Abhijit (which is conducive to victory on all sides); (nay,) all the lunar mansions and other stars as well as the planets (the sun and so on) rendered His birth (most) propitious (by their benign influence). The sun happened to be at the meridian (the point reached by it at midday), O protector of men ! The twelfth day (of the bright half of Bhadrapada), on which the learned know the birth of Sri Hari to have taken place is called by the name of Vijaya-Dwadasi. Conchs and kettledrums (as well as) clay tomtoms, tabors and double drums sounded. (And) there arose a tumultuous din of various wind-instruments and other musical instruments.
Full of joy, Apsaras danced and the chief of the Gandharvas sang; while sages and gods, the Manus, the manes and the fire-gods, hosts of Siddhas and Vidyadharas along with Kimpurusas and Kinnaras, as well as Caranas, Yaksas and Raksasas, Suparnas (the secretary birds) and the foremost of Nagas (too) uttered praises. (And) attendants of gods covered the hermitage of Aditi including the surrounding grounds with showers of flowers, singing and dancing and loud in their praises. Astonished to see that supreme Person having assumed a personality by His wonderful creative energy and sprung from her own womb, Aditi experienced (abundant) joy and the lord of created beings (the sage Kasyapa too) was filled with (great) wonder and exclaimed: "May You be victorious !" In that very form which Lord Sri Had-who is unembodied consciousness-had assumed and which (only a short while ago) was obviously resplendent with jewels and weapons, He, like an actor of wonderful movements, became a short-statured Brahmana boy; (even) while the couple stood gazing. (Greatly) rejoicing to see (the Lord in the form of) that dwarfish Brahmana boy, eminent sages placed the lord of created beings (the sage Kasyapa) at their head and had (all) sacred rites (with respect to that divine Boy) performed (with due ceremony). To Him, when being invested with the sacred thread, Savita (the sun-god, the deity presiding over and invoked through the sacred Gayatri-Mantra) taught the (famous) Gayatri-Mantra (a prayer to the sun-god, which every Dwija is acquired to learn and mutter everyday without fail); the sage Brhaspati (the preceptor of the gods) gave Him the sacred thread (to be worn baldric wise at all times) and the sage Kasyapa (His own father), a sacred cord made of Munja grass (which every Brahmacari is expected to wear round his waist all the time and from which is suspended the strip of cloth covering his privy parts).