Bhagavatapurana 11.29.31

11.29.31

etair doṣair vihīnāya brahmaṇyāya priyāya ca /
sādhave śucaye brūyād bhaktiḥ syāc chūdra-yoṣitām //

31. Thou shouldst teach it only to a person who is free from these defects, who is devoted to brahmins and beloved of them and who is righteous and pious, so that devotion may be produced even in Sudras and women.