Mahabharata 13.75.22

13.75.22

na cāśiṣyāyāvratāyopakuryānnāśraddadhānāya na vakrabuddhaye |
guhyo hyayaṃ sarvalokasya dharmo nemaṃ dharmaṃ yatra tatra prajalpet || 22 ||

Commencing again from that lunation, numbering the eight, which is known by the name of Kamya, he should pass three nights, supporting himself entirely on milk and urine and dung of the cow. By giving away a bull, one attains to the merit that attaches to the divine vow (Brahmacharya). By giving away a couple of kine, one acquires the mastery of the Vedas. That man who performs a sacrifice and makes gifts of kine agreeably to the ritual laid down, attains to many regions of a superior character. These, however, are not attainable by the person who is unacquainted with that ritual (and who, therefore, gives away kine without observing the scriptural declarations). That man who gives away even a single cow that yields a copious measure of milk, acquires the merit of giving away all desirable things on Earth collected together. What need, therefore, be said of the gift of many such kine as yield Havya and Kavya in consequence of their full udders? The merit that attaches to the gift of superior oxen is greater than that which attaches to the gift of kine. One should not, by imparting a knowledge of this ritual, benefit a person that is not one's disciple or that is not observant of vows or that is bereft of faith or that is possessed of a crooked understanding. Verily, this religion is a mystery, unknown to most people. One that knows it should not speak of it at every place. There are, in the world, many men that are bereft of faith.