SB 11.21.28

na te mām aṅga jānanti
 hṛdi-sthaṁ ya idaṁ yataḥ
uktha-śastrā hy asu-tṛpo
 yathā nīhāra-cakṣuṣaḥ
Synonyms: 
na — do not; te — they; mām — Me; aṅga — My dear Uddhava; jānanti — know; hṛdi-stham — seated within the heart; yaḥ — who is; idam — this created universe; yataḥ — from whom it comes; uktha-śastrāḥ — who consider Vedic ritual activities to be praiseworthy, or else, for whom their own ritualistic performances are like the weapon that kills the sacrificial animal; hi — indeed; asu-tṛpaḥ — interested only in sense gratification; yathā — just as; nīhāra — in fog; cakṣuṣaḥ — those whose eyes.
Translation: 
My dear Uddhava, persons dedicated to sense gratification obtained through honoring the Vedic rituals cannot understand that I am situated in everyone’s heart and that the entire universe is nondifferent from Me and emanates from Me. Indeed, they are just like persons whose eyes are covered by fog.
Purport: 

The word uktha-śastrāḥ refers to the chanting of certain Vedic hymns, by which one obtains fruitive results in this world and the next. The word śastra also indicates a weapon, and thus uktha-śastra also means the weapon used in Vedic sacrifice to kill the sacrificial animal. Persons exploiting Vedic knowledge for bodily gratification are slaughtering themselves with the weapon of materialistic religious principles. They are also compared to those trying to see within a dense fog. The false bodily concept of life, in which one ignores the eternal soul within the body, is a dense fog of ignorance that blocks our vision of God. Lord Kṛṣṇa therefore begins His instruction in Bhagavad-gītā by clearing away the dense ignorance of the bodily concept of life. Religion means the law of God. The Lord’s final order, or law, is that every conditioned soul surrender unto Him, learn to serve and love Him, and thus go back home, back to Godhead. This is the process of Kṛṣṇa consciousness.