The fourth gravest rule laid down after twenty years

The fourth of the gravest rules forbids a monastic from falsely claiming to have attained superhuman realization or powers. The sub-commentary on the Vinaya commentary of the Southern tradition says this rule was laid down only after the twentieth year after the Awakening. It also answers a question: Moggallāna had attained realization in the first year, yet this rule was laid down only after the twentieth year, so why does the Vinaya contain the Buddha's ruling that Moggallāna had not broken it? The answer is that even before the rule was laid down, monastics had raised criticisms, and the Buddha therefore gave his explanation.