The Belgic Confession, Article I (6)

4. God is Immutable. The eternal, incomprehensible, invisible God is the Unchangeable One. This immutability of God is already implied especially in the attributes of God's simplicity and eternity, but it may be singled out, on the basis of Scripture, as one of the divine perfections. Even as God is perfectly one in all His perfections, and as He is God from eternity to eternity, so He is perfectly and eternally the same, not subject to change. Abundantly the Scriptures reveal this truth. Our...