You already know the Dharma
Mahapajapati Gotami wanted to join the Sangha and become a nun, but did not understand she had already become one. To teach her what a nun was, the Buddha Gotama repeatedly refused to permit her to join the Sangha or ordain her as a nun. As her confusion and frustration grew, she cut off her hair, put on different clothes, and continued to try to prove herself worthy, acting and living in the way she thought nuns were supposed to act. But no matter what she did, Gotama would not ordain her, or permit her to join the Sangha. Eventually, she asked why? Gotama said he could not permit her to join the Sangha or ordain her as a nun because she already had joined the Sangha and was a nun. She suddenly realized what it was to be a nun! So she then asked Gotama to teach her the Dharma. This Gotama refused to do. She smiled, because she now understood the lesson: Gotama smiled back, "Gotami you already know the Dharma, the Vinaya, my instructions? You know some things lead to the cessation of suffering, you know to seek dispassion, disattachment, modesty, contentment, disentaglement, seclusion, persistence, unburdening ...” She understood what was left was to perfect her training.