Jamieson, Fausset and Brown on 2 Corinthians 13:4

4. though--omitted in some of the oldest manuscripts; then translate, "For He was even crucified," &c.

through weakness--Greek, "from weakness"; that is, His assumption of our weakness was the source, or necessary condition, from which the possibility of His crucifixion flowed (He 2:14; Php 2:7, 8).

by--Greek, "from"; "owing to."

the power of God--the Father (Ro 1:4; 6:4; Ep 1:20).

weak in him--that is, in virtue of our union with Him, and after His pattern, weakness predominates in us for a time (exhibited in our "infirmities" and weak "bodily presence," 2Co 10:10; 12:5, 9, 10; and also in our not putting into immediate exercise our power of punishing offenders, just as Christ for a time kept in abeyance His power).

we shall live with him--not only hereafter with Him, free from our present infirmities, in the resurrection life (Php 3:21), but presently in the exercise of our apostolic authority against offenders, which flows to us in respect to you from the power of God, however "weak" we now seem to you. "With Him," that is, even as He now exercises His power in His glorified resurrection life, after His weakness for a time.