四分律刪繁補闕行事鈔 1.150

1.150

狂等三人，由心無記，故不足。若準律中，常憶常來，不憶不來，此之二人，既不得法；初人成用，後人不足。若互憶忘，及來不來；未得羯磨，不得別他。若得羯磨，縱使病差，則通不足。

The three, including the insane: because their minds are indeterminate, they do not make up the quorum. If according to the Vinaya, one who always remembers and always comes, and one who does not remember and does not come—these two persons both do not receive the procedure; the first person can be used, and the latter person does not make up the quorum. If they alternate between remembering and forgetting, or between coming and not coming: before receiving the karman, one must not set them apart from others; if they receive the karman, even if their illness is cured, they generally do not make up the quorum.