無量壽經優婆提舍願生偈註 1.38

1.38

此二句名莊嚴主功德成就。佛本何故興此願？見有國土，羅剎為君則率土相噉、寶輪駐（立馬，長句反）殿則四域無虞，譬之風靡，豈無本耶？是故興願：願我國土常有法王，法王善力之所住持。住持者，如黃鵠持子安，千齡更起；魚母念持子，逕澩（夏有水、冬無水曰澩，火岳反）不壞。安樂國為正覺善持其國，豈有非正覺事耶？是故言正覺阿彌陀，法王善住持。

These two lines are called the accomplishment of the adornment of the master merits. Why did the Buddha originally give rise to this vow? He saw that there are lands where, if a rākṣasa is ruler, the whole realm devours one another, but if the precious wheel stays in the palace, the four regions have no worries. Like grass bending with the wind, how could there not be a source? For this reason he gave rise to a vow: 'May my land constantly have a Dharma King, sustained by the skillful power of the Dharma King.' Sustaining is like the yellow swan holding its egg peacefully so that after a thousand years it hatches anew, or a mother fish mindfully holding her fry so that passing through shallow drying waters they do not perish. The Land of Peace and Bliss is skillfully sustained by the Perfectly Awakened One; how could there be anything that does not accord with perfect awakening? Therefore it is said: 'The Perfectly Awakened Amitābha, / The Dharma King, skillfully sustains it.'