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, ickly; 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 ickly,' 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 ickly.
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: