Vasishthadharmasutra 11.48

11.48

vijñāyate hi / tribhis ṛṇais ṛṇavān brāhmaṇas jāyate^iti / yajñena devebhyas prajayā pitṛbhyas brahmacaryeṇa ṛṣibhyas ityeṣa vānṛṇas yajvā yas putrī brahmacaryavān iti //

For it is declared in the Veda, 'A Brâhmana is born, loaded with three debts,' (and further, 'He owes) sacrifices to the gods, a son to the manes, the study of the Veda to the Rishis; therefore he is free from debt who has offered sacrifices, who has begotten a son, and who has lived as a student (with a teacher).'