Admission to saṅgha in early times was not ceremonial. The Buddha used to say "ehi " (come, follow me). Later on, those who were thus admitted by him could admit others to the Order. A layman had to complete at least fifteen years of age to become a novice. For the admission to the full monkhood, the novices had to be at least twenty years of age. Admission to saṅgha consisted of two stages marked by two rites, namely, pravrajyā and upasaṃpadā.
Pravrajyā (pabbajjā) is going forth from home, that is renunciation. The term pravrajyā refers to the admission of a novice. It was the first step towards monkhood. He who was admitted was known as novice (śrāmaṇera) or navako bhikkhu, a new monk. He could be admitted only after seeking consent from his parents. The senior monk could admit him without presenting before any formal conclave, and after admission he was associated with a religious teacher (upādhyāya).
The novice had to shave his hair; he had to put on three yellow ragged garments (tri-cīvara) and repeat the following formula three times.
I take refuge in the Buddha [buddhaṃ saraṇam gacchāmi].
I take refuge in the dhamma [dhammaṃ saraṇam gacchāmi].
I take refuge in the Order [saṅgham saraṇam gacchāmi].
He, the novice, was further given instruction in the ten precepts daśa-śīla or sikkhāpada which consisted of ten abstinences (veramaṇī). (For details see under śīla.)