仁王護國般若經疏 5.93

5.93

問：何不如《大品》付囑聲聞、《法華》付囑菩薩，而乃付囑國王耶？答：此佛隨病設藥。以王國有災厄弘宣得益故付囑。又百事大供養深廣，自非王力誰所能辦？故付囑也。又王若不信，法即不行；行法在王，故付之也。

Question: Why is it not like the Pañcaviṃśatisāhasrikā, which entrusts [the teaching] to the śrāvakas, or the Lotus Sūtra, which entrusts it to the bodhisattvas, but instead entrusts it to the kings of realms? Answer: Here the Buddha prescribes medicine according to the sickness. Because kings' realms suffer calamities and disasters, and proclaiming [the sūtra] brings benefit, he therefore entrusts it. Furthermore, the great offerings of a hundred matters are deep and vast; if not for the power of kings, who could manage them? Therefore he entrusts it. In addition, if a king does not have faith, the Dharma will not be practiced; the practice of the Dharma depends on the king, so he entrusts it to them.