無量壽經優婆提舍願生偈註 1.61

1.61

此二句名莊嚴口業功德成就。佛本何故興此莊嚴？見有如來名似不尊，如外道軵（推車，人冡反）稱瞿曇姓，成道日聲唯徹梵天。是故願言：使我成佛，妙聲遐布，聞者悟忍。是故言如來微妙聲，梵響聞十方。

These two lines are called the accomplishment of the adornment of merits of vocal karma. Why did the Buddha originally raise this adornment? He saw that there are Tathāgatas whose names seem not to be revered, such as non-Buddhists pushing their carts and calling him by the surname Gautama, and on the day of his attaining the Way, his voice only reached the Brahma Heaven. Therefore he made the vow: "May it be that when I attain Buddhahood, my wondrous voice spreads far and wide, and those who hear it awaken to receptivity." Therefore it is said: "The Tathāgata's subtle and wondrous voice, / A brahma sound heard in the ten directions."