'Warning' in the Bible

To whom shall I speak, and give warning, that they may hear? behold, their ear is uncircumcised, and they cannot hearken: behold, the word of the LORD is unto them a reproach; they have no delight in it.

Son of man, I have made thee a watchman unto the house of Israel: therefore hear the word at my mouth, and give them warning from me.

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.

Again, When a righteous man doth turn from his righteousness, and commit iniquity, and I lay a stumblingblock before him, he shall die: because thou hast not given him warning, he shall die in his sin, and his righteousness which he hath done shall not be remembered; but his blood will I require at thine hand.

Then whosoever heareth the sound of the trumpet, and taketh not warning; if the sword come, and take him away, his blood shall be upon his own head.

He heard the sound of the trumpet, and took not warning; his blood shall be upon him. But he that taketh warning shall deliver his soul.