Bhagavad Gita Chapter 3 Sloka 13 (3.13)

ಯಜ್ಞಶಿಷ್ಟಾಶಿನಃ ಸಂತೋ ಮುಚ್ಯಂತೇ ಸರ್ವಕಿಲ್ಬಿಷೈಃ ।
ಭುಂಜತೇ ತೇ ತ್ವಘಂ ಪಾಪಾ ಯೇ ಪಚಂತ್ಯಾತ್ಮಕಾರಣಾತ್॥೧೩॥
yajñaśiṣṭāśinaḥ saṃto mucyaṃte sarvakilbiṣaiḥ |
bhuṃjate te tvaghaṃ pāpā ye pacaṃtyātmakāraṇāt||13||
Gist of the sloka:
What is left out, after offering to the demi-Gods, will remove all the sins. One who eats his own food without offering the same to others, is like eating one own’s sins.
Explanation:
One who accepts what comes his way, then offers the same to the Lord and then takes it, will be removed of all sins, from such actions. They will over period of time remove all their sins and will obtain release. Those who cook for themselves and eat it without offering it to Lord, are only eating their own sins.
We need to understand, that the food itself has been given to us by the Lord. We need to show our gratitude to the Lord by first offering it to Him, such a sanctified food is sin free and actually enhances our mental ability and nearness to Him.
Instead if we believe, it’s my earning, my hard work/money, which brought the food to me etc., we are only increasing our sinful load. If we neglect the force which brought us the food, we might even lose what we have. No one helps an ungrateful person.