Chandogya Upanishad 5.24

'If, without knowing this, one offers an Agnihotra, it would be as if a man were to remove the live coals and pour his libation on dead ashes.

'But he who offers this Agnihotra with a full knowledge of its true purport, he offers it (i.e. he eats food) in all worlds, in all beings, in all Selfs.

'As the soft fibres of the Ishîkâ reed, when thrown into the fire, are burnt, thus all his sins are burnt whoever offers this Agnihotra with a full knowledge of its true purport.

'Even if he gives what is left of his food to a Kandâla, it would be offered in his (the Kandâla's) Vaisvânara Self. And so it is said in this Sloka:— 'As hungry children here on earth sit (expectantly) round their mother, so do all beings sit round the Agnihotra, yea, round the Agnihotra.'