When getting ready to perform yajna, on the previous day the performer takes the vow of truth. Satapatha brahmanam says there are only two states - of truth and untruth ( the white lie or the apparently innocent lie is not accepted as something in the middle). Man by nature is untruthful and gods by nature are truthful. The main purpose of performing yajna is to attain heaven or become a God. Veda says -इदमहमनृतात्सत्यमुपैमि - moving from untruthfulness to truthfulness thereby becoming God from man.
All acts of the performer of yajna imitate those of Gods and they reiterate his movement from manliness to Godliness.
Hence the vow to truthfulness.
To be untruthful is to be man and to be truthful is to be God.
All acts of the performer of yajna imitate those of Gods and they reiterate his movement from manliness to Godliness.
Hence the vow to truthfulness.
To be untruthful is to be man and to be truthful is to be God.