大乘起信論義記 2.205

2.205

一者、無明業相。以依不覺故心動，說名為業；覺則不動。動則有苦，果不離因故。

“First is the karmic mark of avidyā. Because the mind is agitated dependent on non-enlightenment, it is called karma; when enlightened, it is unmoved. When there is agitation, there is suffering, because the fruit is not separated from the cause.”