Philippians 2:22 in the King James Version
But ye know the proof of him, that, as a son with the father, he hath served with me in the gospel.
Context
21 For they all seek their own, not the things of Jesus Christ.
22 But you know that he has proved himself. As a child serves a father, so he served with me in furtherance of the Good News.
23 Therefore I hope to send him at once, as soon as I see how it will go with me.