無量壽經優婆提舍願生偈註 2.106

2.106

真如是諸法正體，體如而行則是不行，不行而行名如實修行。體唯一如而義分為四，是故四行以一正統之。

Suchness is the correct substance of all phenomena. When one acts in accordance with suchness, this is non-action; non-action yet acting is called 'practicing in accordance with reality.' The substance is solely a single suchness, but in its meaning it is divided into four; therefore, the four practices are unified by the single 'correct.'