Tanya Chapter 8 part 1. Intentions are powerful and can turn the mundane into something holy, but some realities cannot be altered by intent.

What if someone unwittingly ate forbidden food with the intention of serving Hashem—and even used the energy derived from that food to fuel their Torah study and prayer? Can this energy rise to holiness and become clothed within the words of Torah and prayer?The vitality within forbidden foods is intrinsically tied to the three completely impure kelipot, meaning it cannot be elevated to holiness, no matter how pure one’s intentions. This reflects the Torah’s definition of assur—“tied up”—an objective reality that renders these foods inherently bound to impurity.Permissible foods, by contrast, draw their vitality from kelipat nogah and can be elevated to holiness when approached with proper intent. However, indulging in them solely for self-gratification temporarily drags them into impurity, leaving a lasting imprint even after a person realigns themselves with holiness. This residual impurity requires chibut hakever, the “beating of the grave,” to divest the body of its attachment to worldly pleasures.