法華論疏 3.455

3.455

言說力者，佛為十方世界眾生說法，故名說力。亦是謦欬中說偈，令十方世界聞，名為說力。

Regarding the expression "power of exposition": the Buddha expounds the Dharma for sentient beings of the worlds of the ten directions; hence it is named the "power of exposition". It also means expounding verses while coughing, causing the worlds of the ten directions to hear them; this is named the "power of exposition".