श्रीमद् भगवद्गीता

English Translation of Ramanuja's Sanskrit Commentary By Swami Adidevananda

3.12 'Pleased by the sacrifice,' i.e., propitiated by the sacrifice, the gods, who have Me as their Self, will bestow on you the enjoyments you desire. Whatever objects are desired by persons keen on attaining release, the supreme end of human endeavour, all those will be granted by gods previously worshipped through many sacrifices. That is, whatever is solicited with more and more propitiation, all those enjoyments they will bestow on you. Whoever enjoys the objects of enjoyment granted by them for the purpose of worshipping them, without giving them their due share in return - he is verily a thief. What is called 'theft' is indeed taking what belongs to another as one's own and using it for oneself, when it is really designed for the purpose of another. The purport is that such a person becomes unfit not only for the supreme end of human endeavour, but also will go down towards purgatory (Naraka). Sri Krsna expands the same:

English Translation Of Sri Shankaracharya's Sanskrit Commentary By Swami Gambirananda

3.12 'Yajna-bhavitah, being nourished, i.e. being satisfied, by sacrifices; devah, the gods; dasyante hi, will indeed give, will distribute; among vah, you; the istan, coveted; bhogan, enjoyments, such as wife, childeren and cattle. Sah, he; is eva, certainly; a stenah, thief, a stealer of the wealth of gods and others; yah, who; bhunkte, enjoys, gratifies only his own body and organs; with dattan, what enjoyable things have been given; taih, by them, by the gods; apradaya, without offering (these); hyah, to them, i.e. without repaying the d [The three kinds of d -to the gods, to the rsis (sage), and to the manes-are repaid by satisfying them through sacrifices, celibacy (including study of the Vedas, etc.), and procreation, respectively. Unless one repays these d s, he incurs sin.] to them.'