Vishnupurana 3.18.p14

3.18.p14

I have thus described to you, O Maitreya, the sin consequent upon conversing with a heretic and effects of bathing after the solemn sacrifice of a horse. A man should therefore carefully avoid the conversation or coming in contact with a heretic especially at seasons of devotion and when engaged in the performance of the religious rites before a sacrifice. The prudent should look at the sun after seeing a person in whose house domestic ceremonies have been neglected for a month. And there is the greatest need of expiation if they meet persons who live upon other's rice and who have wholly abandoned the Vedas and who dispute the doctrines of sacred writings. A man should not even talk with heretics, those who do forbidden acts, pretended saints, scoundrels, sceptics and hypocrites; communication with such sinful wretches ever at a distance, all association with schismatics pollutes a man; a man should therefore carefully avoid them.