無量壽經優婆提舍願生偈註 1.67

1.67

此二句名莊嚴上首功德成就。佛本何故起此願？見有如來，眾中或有強梁者，如提婆達多流比；或有國王與佛並治，不知甚推佛；或有請佛，以他緣廢忘。有如是等，似上首力不成就。是故願言：我為佛時，願一切大眾無能生心敢與我等，唯一法王更無俗王。是故言如須彌山王，勝妙無過者。

These two lines are called the accomplishment of the adornment of merits of the foremost leader. Why did the Buddha originally raise this vow? He saw that among the assemblies of certain Tathāgatas there may be rebellious ones, like Devadatta and his peers; or there may be worldly kings governing alongside the Buddha who do not know how to venerate the Buddha deeply; or there may be those who invite the Buddha but neglect and forget him due to other conditions. There being such things, the power of being the foremost leader seemed unaccomplished. Therefore he made the vow: "When I become a Buddha, I vow that none in all the great assembly shall dare conceive a mind to be equal to me; there shall be only one Dharma King and no further secular king." Therefore it is said: "Like the King of Mount Sumeru, / Exquisite and unsurpassed."