大般涅槃經義記 3.144

3.144

自下文中教以四觀撿驗其行，於中三喻：初田夫喻，教其共住久處撿驗；第二林喻，教以智慧；第三藥喻，教以觀察。

In the text below, it teaches using the four observations to scrutinize and verify their conduct; within this are three analogies: first, the farmer analogy, which teaches scrutinizing and verifying through living together and dwelling for a long time; second, the forest analogy, which teaches through wisdom; third, the medicine analogy, which teaches through examination.