Bhagavad Gita 3.13
यज्ञशिष्टाशिन: सन्तो मुच्यन्ते सर्वकिल्बिषै: |
भुञ्जते ते त्वघं पापा ये पचन्त्यात्मकारणात् ||
yajna-shishtashinah santo muchyante sarva-kilbishaih
bhunjate te tvagham papa ye pachantyatma-karanat
The spiritually-minded, who eat food that is first offered in sacrifice, are released from all kinds of sin.
Others, who cook food for their own enjoyment, verily eat only sin.
Every food inevitably involves violence.
Obviously non-vegetarian food eaters enjoy the flesh of a murdered animal that suffered in great fear and pain.
But even vegetarian food causes some pain to plants, animals that get crushed under tractor, insects/microbes that get drowned or burned while cooking etc.
To avoid this sin, there are 2 ways :
- Don't eat anything. This method is followed by Jain monks who simply give up their body and die.
- Offer food as sacrifice (yagna, puja) to Bhagavan, who pardons the sin. This method is followed by almost every religion/sect - Brahmins (Pariseshan), Hindus (Nivedan/Prasad), Muslims (bismillah), Christians (grace).
There are varying levels in-between, where some only eat Uncha-Vritthi (only gathering grains and fruits that have automatically fallen on ground), Kapota-Vritthi (only buying/saving food for 1 day, not caring about tomorrow), Ajagara-Vritthi (only eating whatever falls on their lap)
Pancha-Maha-Yagna or 5 great sacrifices are ordained as part of daily life for a Gruhastha (householder), in order to absolve oneself of sin that occurs in 5 places during daily life (cooking, cutting, sweeping, storing, one more i forget) :
Brahma yagna (to Bhagavan & Rishis)
Deva Yagna (to devas)
Pitru Yagna (to ancestors)
Manushya Yagna (to relatives)
Bhuta Yagna (to animals)