'Testifies' in the Bible

He testifies about what he has seen and heard, yet no one accepts his testimony.

There is another who testifies about me, and I know that the testimony he gives about me is true.

The Spirit himself testifies with our spirit that we are God's children.

For this is what we boast about: Our conscience testifies that we have conducted ourselves in the world with pure motives and godly sincerity, without earthly wisdom but with God's grace especially toward you.