Deuteronomy 13:8

Thou shall not consent unto him
To commit the idolatry enticed unto, or join with him in it:

nor hearken to him;
not so much as patiently to hear him, but at once express an abhorrence of and indignation at what he recommends:

neither shall thine eye pity him;
pitied he might be for his ignorance, stupidity, and wickedness, and on account of the miserable estate and condition he was in, and of those dreadful consequences which would follow upon it, if not converted from it; but no mercy was to be shown him on account of nearness of relation:

neither shall thou spare;
to reprove him sharply and to expose him to public vengeance:

neither shall thou conceal him;
neither him nor his sin, but make both public, acquaint others with it, and endeavour to bring him before the civil magistrate to be examined, tried, and judged; so far should they be from hiding his offence from others, or excusing and extenuating it, or from harbouring his person privately when sought for upon information.