Śatapatha Brāhmaṇa ("of a hundred paths") 11.3.3.6

11.3.3.6

atha yadācāryavacasaṃ karoti yadācāryāya karma karoti ya evāsyācārye pādastameva tena parikrīṇāti taṃ saṃskṛtyānmandhatte sa enamāviśati

And when he does the teacher's bidding, and when he does any work for the teacher, he redeems that part of his which is in the teacher; and, having cleansed it, he takes it to himself, and it enters him.