無量壽經優婆提舍願生偈註 2.91

2.91

何者莊嚴心業功德成就？偈言「同地水火風虛空無分別」故。無分別者，無分別心故。

What is the accomplishment of the adornment of the merits of mental action? Because the verse says: “Like earth, water, fire, wind, and space, it is without discrimination.” 'Without discrimination' means because of the non-discriminating mind.