SB 11.5.14

ye tv anevaṁ-vido ’santaḥ
 stabdhāḥ sad-abhimāninaḥ
paśūn druhyanti viśrabdhāḥ
 pretya khādanti te ca tān
Synonyms: 
ye — those who; tu — but; anevam-vidaḥ — not knowing these facts; asantaḥ — very impious; stabdhāḥ — presumptuous; sat-abhimāninaḥ — considering themselves saintly; paśūn — animals; druhyanti — they harm; viśrabdhāḥ — being innocently trusted; pretya — after leaving this present body; khādanti — they eat; te — those animals; ca — and; tān — them.
Translation: 
Those sinful persons who are ignorant of actual religious principles, yet consider themselves to be completely pious, without compunction commit violence against innocent animals who are fully trusting in them. In their next lives, such sinful persons will be eaten by the same creatures they have killed in this world.
Purport: 

In this verse we can clearly see the great discrepancies in those persons who do not surrender to the Supreme Personality of Godhead and His law. As stated in the Bhāgavatam, harāv abhaktasya kuto mahad-guṇāḥ: those who do not accept the supremacy of the Supreme Lord gradually become infected with the most sinful propensities that bring, in their turn, terrible suffering upon the nondevotees. In the Western countries such as America, many people proudly proclaim themselves to be most pious religionists and sometimes even prophets or representatives of God. Boasting of their religiosity, such foolish people experience no fear or doubt in cruelly slaughtering innumerable animals in slaughterhouses or on hunting trips for their whimsical sense gratification. In the state of Mississippi there are sometimes pig-killing festivals, in which entire families enjoy watching a pig cruelly butchered before their eyes. Similarly, a former president of the United States from Texas did not consider any social occasion complete without the slaughtering of a cow. Such persons mistakenly consider themselves to be perfectly observing the laws of God and due to such arrogant foolishness lose all touch with reality. When a man is raising an animal for slaughter, he feeds the animal nicely and encourages it to grow fat. Thus the animal gradually accepts its would-be killer as its protector and master. When the master finally approaches the helpless animal with a sharp knife or gun, the animal thinks, “Oh, my master is joking with me.” Only at the last minute does the animal understand that the so-called master is death personified. It is clearly stated in Vedic literature that cruel masters who kill innocent animals will undoubtedly be killed in the next life by a similar process.

māṁ sa bhakṣayitāmutra
 yasya māṁsam ihādmy aham
etan māṁsasya māṁsatvaṁ
 pravadanti manīṣiṇaḥ

“‘That creature whose flesh I am eating here and now will consume me in the next life.’ Thus meat is called māṁsa, as described by learned authorities.” In Śrīmad-Bhāgavatam this grisly fate of animal killers is described by Nārada Muni to King Prācīnabarhi, who was excessively killing animals in so-called sacrifices.

bho bhoḥ prajāpate rājan
 paśūn paśya tvayādhvare
saṁjñāpitān jīva-saṅghān
 nirghṛṇena sahasraśaḥ

ete tvāṁ sampratīkṣante
 smaranto vaiśasaṁ tava
samparetam ayaḥ-kūṭaiś
 chindanty utthita-manyavaḥ

“O ruler of the citizens, my dear King, please see in the sky those animals which you have sacrificed, without compassion and without mercy, in the sacrificial arena. All these animals are awaiting your death so that they can avenge the injuries you have inflicted upon them. After you die, they will angrily pierce your body with iron horns.” (Bhāg. 4.25.7-8) Such punishment of animal killers may take place under the jurisdiction of Yamarāja on the planet of the lord of death. In other words, one who kills an animal or who eats meat undoubtedly acquires a debt to the living entity who has contributed his body for the satisfaction of the meat-eater. The meat-eater must pay his debt by contributing his own body to be consumed in the next life. Such payment of one’s debt by offering one’s own body to be eaten is confirmed in the Vedic literature.