kāńkṣantaḥ karmaṇāḿ siddhiḿ
yajanta iha devatāḥ
kṣipraḿ hi mānuṣe loke
siddhir bhavati karma-jā

Translation of Bhagavad Gita 4.12

Men in this world desire success in fruitive activities, and therefore they worship the demigods. Quickly, of course, men get results from fruitive work in this world.

Commentary by Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

There is a great misconception about the gods or demigods of this material world, and men of less intelligence, although passing as great scholars, take these demigods to be various forms of the Supreme Lord. Actually, the demigods are not different forms of God, but they are God’s different parts and parcels. God is one, and the parts and parcels are many. The Vedas say, nityo nityanam: God is one. Ishvarah paramah krishnah. The Supreme God is one—Krishna—and the demigods are delegated with powers to manage this material world. These demigods are all living entities (nityanam) with different grades of material power. They cannot be equal to the Supreme God—Narayana, Vishnu, or Krishna. Anyone who thinks that God and the demigods are on the same level is called an atheist, or pasandi. Even the great demigods like Brahma and Shiva cannot be compared to the Supreme Lord. In fact, the Lord is worshiped by demigods such as Brahma and Shiva (shiva-virinci-nutam). Yet curiously enough there are many human leaders who are worshiped by foolish men under the misunderstanding of anthropomorphism or zoomorphism. Iha devatah denotes a powerful man or demigod of this material world. But Narayana, Vishnu, or Krishna, the Supreme Personality of Godhead, does not belong to this world. He is above, or transcendental to, material creation. Even Sripada Shankaracarya, the leader of the impersonalists, maintains that Narayana, or Krishna, is beyond this material creation. However, foolish people (hrta-jnana) worship the demigods because they want immediate results. They get the results, but do not know that results so obtained are temporary and are meant for less intelligent persons. The intelligent person is in Krishna consciousness, and he has no need to worship the paltry demigods for some immediate, temporary benefit. The demigods of this material world, as well as their worshipers, will vanish with the annihilation of this material world. The boons of the demigods are material and temporary. Both the material worlds and their inhabitants, including the demigods and their worshipers, are bubbles in the cosmic ocean. In this world, however, human society is mad after temporary things such as the material opulence of possessing land, family and enjoyable paraphernalia. To achieve such temporary things, people worship the demigods or powerful men in human society. If a man gets some ministership in the government by worshiping a political leader, he considers that he has achieved a great boon. All of them are therefore kowtowing to the so-called leaders or “big guns” in order to achieve temporary boons, and they indeed achieve such things. Such foolish men are not interested in Krishna consciousness for the permanent solution to the hardships of material existence. They are all after sense enjoyment, and to get a little facility for sense enjoyment they are attracted to worship empowered living entities known as demigods. This verse indicates that people are rarely interested in Krishna consciousness. They are mostly interested in material enjoyment, and therefore they worship some powerful living entity.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

However, among men, those who are full of desire give up the path of bhakti even though it is coming directly from me, and follow the path of karma which gives quick results. That is explained in this verse. The results of their actions (karma ja siddhih) such as going to svarga, come quickly.

Commentary by Sri Ramanuja of Sri Sampradaya:

4.12 All men, desirous of the fruits of their actions, ‘sacrifice’, i.e., worship or propitiate Indra and other divinities only. But nobody worships Me abandoning attachment to fruits — Me, who am the Self of Indra and other divinities and the real enjoyer of all sacrifices. Why is this so? Because in this world of men, fruits in the form of sons, cattle, food etc., follow soon from their performance of such sacrificial rites. The phrase, ‘the world of men’ implies heaven etc., also. Because the unending accumulation of evil heaped up from beginningless time has not been exhausted, all those worldly people lack discernment. Therefore they want rapid results and perform those rituals which consist of the worship of Indra and other divinities for the sake of sons, cattle, food etc., and for the sake of heaven etc. But none with his mind anguished by Samsara and aspiring for final release, practises Karma Yoga of the kind described above. Real Karma Yoga is My worship. Sri Krsna now speaks of the cause which annuls the evil obstructing the starting of Karma Yoga.

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

It may be questioned that since Lord Krishna is the exclusive awarder of moksa or liberation from the cycle of birth and death; then why is it that most people are obliviously worshipping lesser gods instead of Him? The reason He answers is factual. People worship the lesser gods because they desire material benefits which is what the lesser gods can give. Worshipping lesser gods for wealth, dominion, a beautiful wife, a powerful son, such efforts easily bring quick results and the desired rewards. But moksa or liberation is only achieved as a result of cultivating Vedic knowledge about the Supreme Lord and thus it is hard to attain.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

Those that are worshipping the demi-gods and other religions and denominations, how can they be understood to be following Lord Krishna’s path? The proof is given in the second half of this verse being: quick indeed do they get their desired fruits from such worship. This is confirmed in the Chandogya Upanisad where it states: tasya ime venayam gayanti, tasmat te dhanasanayah which clarifies that from the Supreme Lord alone are bequeathed the rewards of one’s actions.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

It may be further asked that if Lord Krishna is the exclusive bestower of the goal of life then why is not every one following Him. To alleviate such a doubt Lord Krishna answers that most people are engaged in karma yoga or the performance of prescribed duties of their caste and station. Performing myriad of actions they seek material results from their efforts. These material benefits are beseeched in the forms of wealth, power, good health and such. For these things they worship lesser gods for quick results and not Lord Krishna. But for moksa or liberation the results do not come quickly as this knowledge must refined and perfected picking up where one left off in a previous birth through many lifetimes. The purport is that most people worship various others because in their present life they have no knowledge of and no intrinsic interest in moksa.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

4.12 Kanksantah, longing for, praying for; siddim, fruition, fructification of the results; karmanam, of actions; yajante, they worship; iha, here, in this world; devatah, the gods, Indra, Fire and others- which accords with the Upanisadic text, ‘While he who worships another god thinking, “He is one, and I am another,” does not know. He is like an animal to the gods’ (Br. 1.4.10). [This text points out that the reason for adoring other deties is the ignorance of the Self, which gives rise to the ideas of difference between the worshipped and the worshipper. As animals are beneficial to human beings, so also is the sacrificer to the gods, because through oblations he works for their pleasure!] Hi, for, in the case of those, indeed, who sacrifice to other gods and long for results; (siddhih, success; karmaja, from action;) bhavati, comes; ksiparm, quickly; manuse-loke, in the human world, because the authority of the scriptures extends only over the human world. By the specific statement, ‘For, in the human world, success comes quickly,’ the Lord shows that results of actions can accrue even in the other worlds. The difference lies in this that, in the human world eligibility for [Ast. and A.A. omit ‘adhikara, elegibility for’, and read karmani.-Tr.] actions is according to castes, stages of life, etc. The fruition of the results of those actions of persons who are eligible according to castes, stages of life, etc. comes quickly. What is the reason for the rule that the competence for rites and duties according to castes, stages of life, etc. obtains only in the human world, but not in the other worlds? Or:-It has been said, ‘Human beings, having such divisions as castes, stages of life, etc., follow My path in every way.’ For what reason, again, do they as a rule follow Your path alone, but not of others? This is being answered:

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

4.11-12 Ye yatha etc. and Kanksantah etc. Different persons with differents forms in their mind take refuge in Me. Assuming the same [respective] forms for them I favour the. Only in this manner, those who are full of Me and those who are not so-all just follow my Path. For [even the performance of sacrifices] Jyotistoma and so on, is not a different path; that is also My own will of that nature. Indeed it is going to be declared [by the Lord] as ‘the four-fold caste-structure has been created by Me’. Some one says : The Present Tense (anuvarttante) is in the sense of Potential. Just as in the sentence ‘They take hold of the group of sixteen in the Atiratra [sacrifce]’, the expression ‘They take hold of’ means ‘They should take hold of’ in the same way in the present sentence too ‘they follow’, means ‘they should follow’. The success [of the action] viz., the enjoyment and emancipation is [achieved] here alone in this word of men and not anywhere else.

Sanskrit Shloka Without Transliteration Marks:

kanksantah karmanam siddhim
yajanta iha devatah
ksipram hi manuse loke
siddhir bhavati karma-ja

Sanskrit to English Word for Word Meanings:

kāńkṣantaḥ — desiring; karmaṇām — of fruitive activities; siddhim — perfection; yajante — they worship by sacrifices; iha — in the material world; devatāḥ — the demigods; kṣipram — very quickly; hi — certainly; mānuṣe — in human society; loke — within this world; siddhiḥ — success; bhavati — comes; karma-jā — from fruitive work.