The Long Āgama Sūtra 28.61

28.61

佛告梵志：「若有異學欲於我法中出家為道者，先四月觀察，稱眾人意，然後乃得出家受戒。雖有是法，亦觀人耳。」

The Buddha told the wanderer, “If someone of a different training wants to leave home for the path in my Dharma, they’re first observed for four months, and then the assembly gives their assent. After that, they are given the precepts and leave home. While there’s this rule, the person is just observed.”