大般涅槃經義記 4.172

4.172

二重勸不用，以法對機義稱「醫答」，聞經不受名「不見信」，勸修治法是故說言「應服下藥」，障除乃覺故言「下後王自驗之」，彼聞不用名「不肯服」。

Second, repeatedly exhorting, but not being accepted: matching the Dharma to the capacity is figuratively called "the physician answered"; hearing the sūtra and not accepting it is called "not being believed"; exhorting the practice of the curative method is why it says "you should take purgative medicine"; realizing it only after obstacles are removed is why it says "after purging, the king will verify it himself"; hearing it and not using it is called "unwilling to take it."