仁王般若經疏 3.158

3.158

大王吾今下，第七勸受持此經。文有三：初明付囑諸國王；二列十六國；如是一切下，第三勸受持。此經但明十七國，那云十六？答：《大雲經》有十六大國也。

From 'Great King! I now' onward is the seventh [section], encouraging the accepting and upholding of this sūtra. The text has three parts: first, explaining the entrustment to all the kings; second, listing the sixteen states; from 'all such' onward, third, encouraging acceptance and upholding. This sūtra mentions only seventeen states; why does it say sixteen? Answer: The Mahāmegha Sūtra speaks of sixteen great states.