From the Bible:
Gospel of St. Matthew, Chapter 7, Jesus warns:
Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Wherefore by their fruits ye shall know them.
From the Bhagavad Gita, second Chapter:
The sage who knows God has as little need for the Scriptures as one might have for a pond when the whole land is covered in flood.