The works of Ādi Śaṅkarācārya

Sanatsujātīyam

p. 257

p. 257

एतत्समृद्धमत्यर्थं तपो भवति केवलम् ॥ ३२ ॥

In plain words

This, grown full past all measure, becomes tapas — sheer tapas, nothing mixed in.

Close to the Sanskrit

This, exceedingly full-grown, becomes austerity alone.