Mahabharata 13.65.44

13.65.44

amṛtaṃ vai gavāṃ kṣīramityāha tridaśādhipaḥ |
tasmāddadāti yo dhenumamṛtaṃ sa prayacchati || 44 ||

The very chief of the deities had said that the milk of kine is nectar. For this reason, one who makes a gift of a cow is regarded as making a gift of nectar. Persons conversant with the Vedas have declared that the Ghee manufactured from cows' milk is the very best of all libations poured into the sacrificial fire. For this reason, the man who makes a gift of a cow is regarded as making a gift of a libation for sacrifice. A bovine bull is the embodiment of heaven. He who makes the gift of a bovine bull unto an accomplished Brahmana, receives great honours in heaven. Kine, O chief of Bharata's race, are said to be the life-breath of living creatures. Hence, the man who makes the gift of a cow is said to make the gift of life-breath. Persons conversant with the Vedas have said that kine constitute the great refuge of living creatures. Hence, the man who makes the gift of a cow is regarded as making the gift of what is the high refuge for all creatures. The cow should never be given away for slaughter (i.e., unto one who will kill her); nor should the cow be given unto a tiller of the soil; nor should the cow be given unto an atheist. The cow should not also, O chief of the Bharatas, be given unto one whose occupation is the keeping of kine. The wise have said that a person who gives away the cow unto any of such sinful persons has to sink into everlasting hell.