At one time on the observance day, there were three monks staying in a certain monastery. They thought, “The Buddha has instructed that the Monastic Code should be recited when there are four monks. But there’s only three of us. So how should we do the observance-day ceremony?” “When there are three of you, you should do the observance-day ceremony by declaring your purity.

And you should do it like this. A competent and capable monk should inform those monks: ‘Please, venerables, I ask you to listen. Today is the observance day, the fifteenth. If the venerables are ready, we should do the observance-day ceremony by declaring purity to one another.’ The most senior monk should arrange his upper robe over one shoulder, squat on his heels, raise his joined palms, and say to the other monks: ‘I’m pure. Please remember me as pure.’ And he should repeat this two more times.

Each junior monk should arrange his upper robe over one shoulder, squat on his heels, raise his joined palms, and say to the other monks: ‘I’m pure, venerable. Please remember me as pure.’ And he should repeat this two more times.”