Witsius, commenting on the Covenant of Redemption:
“The Son, as precisely God, neither was, nor could be subject to any law, to any superior; that being contrary to the nature of God-head, which we now suppose the Son to have common with the Father. ‘He thought it no robbery to be equal with God’. No subjection, nothing but the high super-eminence can be conceived of the Deity. In this respect he is King of kings and Lord of lords. […] Nor is it any objection against this, that the Son, from eternity, undertook for men, and thereby came under a certain peculiar relation to those that were to be saved. For, as that engagement was nothing but the most glorious act of the divine will of the Son, doing what none but God could do, it implies therefore no manner of subjection: it only imports, that there should be a time, when that divine person, on assuming flesh, would appear in the form of a servant. And by undertaking to perform this obedience, in the human nature, in the proper time, the Son, as God, did no more subject himself to the Father, than the Father with respect to the Son, to the owing that reward of debt, which he promised him a right to claim. All these things are to be conceived of in a manner becoming of God” (Economy, II.iii.6-7).