"God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good? " - Numbers 23:8-10
The following sermons are on Numbers 23:19,20:
God's Sincere Confession, by Rev. Foppe VanderZwaag
The Unchanging God, by Pastor Robert McCurley
The Faithfulness of God, by Rev. G. R. Procee
The Question to Confirm the Faithfulness of God's Word, by Rev. Lawrence J. Bilkes