The Great Epic of the Bhārata dynasty 3.180.36

3.180.36

vṛttaṃ vaidikasaṃskāro yadi na vidyate tarhi sarvāḥ prajāḥ kṛtakṛtyāḥ śūdratulyāḥ | tathā ca smṛtiḥ - ’na śūdre pātakaṃ kiñcinna ca saṃskāramarhati’ iti teṣāṃ saṃskārānarhatvaniṣpāpatvābhidhānāt kṛtakṛtyatvaṃ darśayati | tadvat traivarṇikā api syurityarthaḥ | atra vṛttābhāve ||

If [proper] conduct, [namely] Vedic purificatory rites, does not exist, then all creatures would have fulfilled their obligations, being equal to Śūdras. And likewise the Smṛti says: "There is no sin in a Śūdra, nor does he deserve a purificatory rite"; by stating their unfitness for rites and freedom from sin, it demonstrates their state of having fulfilled their obligations. The meaning is that the members of the three higher classes would also become like that. "Here, in the absence of [proper] conduct" [is the sense].