1 Corinthians 2:4

And my language and the Message that I proclaimed were not adorned with persuasive words of earthly wisdom, but depended upon truths which the Spirit taught and mightily carried home;

Romans 15:19

with power manifested in signs and marvels, and through the power of the Holy Spirit. But--to speak simply of my own labours--beginning in Jerusalem and the outlying districts, I have proclaimed without reserve, even as far as Illyricum, the Good News of the Christ;

1 Corinthians 4:20

For Apostolic authority is not a thing of words, but of power.

1 Corinthians 1:17

Christ did not send me to baptize, but to proclaim the Good News; and not in merely wise words--lest the Cross of Christ should be deprived of its power.

1 Corinthians 2:1

And as for myself, brethren, when I came to you, it was not with surpassing power of eloquence or earthly wisdom that I came, announcing to you that which God had commanded me to bear witness to.

1 Corinthians 2:13

Of these we speak--not in language which man's wisdom teaches us, but in that which the Spirit teaches--adapting, as we do, spiritual words to spiritual truths.

1 Thessalonians 1:5

The Good News that we brought you did not come to you in words only, but also with power and with the Holy Spirit and with much certainty, for you know the sort of men we became among you, as examples for your sakes.

2 Peter 1:16

For when we made known to you the power and Coming of our Lord Jesus Christ, we were not eagerly following cleverly devised legends, but we had been eye-witnesses of His majesty.

John 16:8-15

And He, when He comes, will convict the world in respect of sin, of righteousness, and of judgement; --

Acts 20:27

For I have not shrunk from declaring to you God's whole truth.

Acts 26:28

Agrippa answered, "In brief, you are doing your best to persuade me to become a Christian."

Romans 16:18

For men of that stamp are not bondservants of Christ our Lord, but are slaves to their own appetites; and by their plausible words and their flattery they utterly deceive the minds of the simple.

Galatians 1:10

For is it man's favour or God's that I aspire to? Or am I seeking to please men? If I were still a man-pleaser, I should not be Christ's bondservant.

Colossians 2:4

I say this to prevent your being misled by any one's plausible sophistry.

1 Peter 1:12

To them it was revealed that they were serving not themselves but you, when they foretold the very things which have now been openly declared to you by those who, having been taught by the Holy Spirit which had been sent from Heaven, brought you the Good News. Angels long to stoop and look into these things.

2 Peter 2:18

For, while they pour out their frivolous and arrogant talk, they use earthly cravings--every kind of immorality--as a bait to entrap men who are just escaping from the influence of those who live in error.

Treasury of Scripture Knowledge

Summary

And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power:

My speech

General references

Bible References

My speech

Acts 20:27
For I have not shrunk from declaring to you God's whole truth.

General references

Luke 4:32
And they were greatly impressed by His teaching, because He spoke with the language of authority.
1 Corinthians 4:20
For Apostolic authority is not a thing of words, but of power.