'Preaching' in the Bible

For since, in the wisdom of God, the world through its wisdom did not know God, God was pleased through the foolishness of preaching to save those who believe.

and my speech and my preaching [were] not with the persuasiveness of wisdom, but with a demonstration of the Spirit and power,

But I discipline my body and subjugate [it], lest somehow [after] preaching to others, myself should become disqualified.

But if Christ has not been raised, then our preaching [is] in vain, and your faith [is] in vain.