Dharmaguptaka-vinaya 17.21

17.21

彼比丘不知年滿二十不滿二十，後乃知不滿二十，或作波逸提懺者、或有疑者，佛言：「不知者無犯。自今已去當如是結戒：年滿二十應受大戒，若比丘知年不滿二十與受大戒，此人不得戒，彼比丘可呵癡故，波逸提。」

When bhikṣus did not know whether [a candidate] had reached twenty years or had not reached twenty years, and only later learned that he had not reached twenty, some made pāyattika confession and some had doubts. The Buddha said: "For one who did not know, there is anāpatti. From this day forward, the precept should be laid down thus: 'One who has reached twenty years of age should receive upasampadā. If a bhikṣu, knowing that [a person's] age has not reached twenty, confers upasampadā on him, this person does not obtain the precepts, and that bhikṣu is reproachable on account of foolishness: this is a pāyattika.'"