Verses with the word warn in the Old Testament (8 verses):
2 Chronicles 19:10
And what cause soever shall come to you of your brethren that dwell in your cities, between blood and blood, between law and commandment, statutes and judgments, ye shall even warn them that they trespass not against the LORD, and so wrath come upon you, and upon your brethren: this do, and ye shall not trespass.
When I say unto the wicked, Thou shalt surely die; and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand.
Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul.
Nevertheless if thou warn the righteous man, that the righteous sin not, and he doth not sin, he shall surely live, because he is warned; also thou hast delivered thy soul.
If when he seeth the sword come upon the land, he blow the trumpet, and warn the people;
So thou, O son of man, I have set thee a watchman unto the house of Israel; therefore thou shalt hear the word at my mouth, and warn them from me.
When I say unto the wicked, O wicked man, thou shalt surely die; if thou dost not speak to warn the wicked from his way, that wicked man shall die in his iniquity; but his blood will I require at thine hand.
Nevertheless, if thou warn the wicked of his way to turn from it; if he do not turn from his way, he shall die in his iniquity; but thou hast delivered thy soul.