Bg 3.31

ye me matam idam nityam
anutisthanti manavah
sraddhavanto ’nasuyanto
mucyante te ’pi karmabhih

Word for word: 
ye — those who; me — My; matam — injunctions; idam — these; nityam — as an eternal function; anutisthanti — execute regularly; manavah — human beings; sraddha-vantah — with faith and devotion; anasuyantah — without envy; mucyante — become free; te — all of them; api — even; karmabhih — from the bondage of the law of fruitive actions.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Those persons who execute their duties according to My injunctions and who follow this teaching faithfully, without envy, become free from the bondage of fruitive actions.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The injunction of the Supreme Personality of Godhead, Krishna, is the essence of all Vedic wisdom and therefore is eternally true without exception. As the Vedas are eternal, so this truth of Krishna consciousness is also eternal. One should have firm faith in this injunction, without envying the Lord. There are many philosophers who write comments on the Bhagavad-gita but have no faith in Krishna. They will never be liberated from the bondage of fruitive action. But an ordinary man with firm faith in the eternal injunctions of the Lord, even though unable to execute such orders, becomes liberated from the bondage of the law of karma. In the beginning of Krishna consciousness, one may not fully discharge the injunctions of the Lord, but because one is not resentful of this principle and works sincerely without consideration of defeat and hopelessness, he will surely be promoted to the stage of pure Krishna consciousness.