Charles Spurgeon Commentary Matthew 10:19

"But when they deliver you up, be not anxious how or what ye shall speak: for it shall be given you in that hour what ye shall speak." — Matthew 10:19 (ASV)

When you are before the judge, or about to be there, do not worry yourself about what you shall speak. Do not be anxious regarding your manner or matter when on your defense. If you are the Lord’s true servant, you are the spokesman of the Holy Spirit. He will work in you a peaceful frame of mind, and fitting words shall be given you. He will speak in you and through you. The Father Himself will put into your mouth, at the moment, the most fitting reply to your adversaries.

This has been wonderfully true in past ages in the cases of martyrs for the sake of truth, and bold defenders of the faith still receive the same kind of guidance. Simple peasants have confounded great philosophers, and humble women have left learned ecclesiastics nonplussed.