John Trapp on Isaiah 55:4

Ver. 4. Behold I have given him] i. e. Chriſt called David, ver. 3. becauſe typed out by David, promiſed to him, and ſprang of him.

For a witneſſe] To teach and teſtifie his Fathers will and counſel, at which, Ʋt de veritate hac & voluntate Patris teſtaretur. being his eternal wiſdom, he had been preſent. See Rev. 3.14.

A Leader and Commander to the people] Of Chriſts Prieſtly office had been ſpoken, chap. 53. here of his Prophetical and Princely. Theſe were frequently ſet forth even in the Old Teſtament: by the Crown or golden plate on the high-Prieſts head was ſignified Chriſts Kingly office: by the breaſt plate his Prieſtly, and by the bells his Prophetical.