Jamieson, Fausset and Brown on Ephesians 3:17

17. That--So that.

dwell--abidingly make His abode (Joh 14:23). Where the Spirit is there Christ is (Joh 14:16, 18).

by faith--Greek, "through faith," which opens the door of the heart to Jesus (Joh 3:20). It is not enough that He be on the tongue, or flit through the brain: the heart is His proper seat [Calvin]. "You being rooted and grounded in love" (compare Ep 3:19), is in the Greek connected with this clause, not with the clause, "that ye may be able to comprehend." "Rooted" is an image from a tree; "grounded" (Greek, "founder," "having your foundations resting on"), from a building (compare Notes,, see on Ep 2:20,21; Col 1:23; 2:7). Contrast Mt 13:6, 21. "Love," the first-fruit of the Spirit, flowing from Christ's love realized in the soul, was to be the basis on which should rest their further comprehension of all the vastness of Christ's love.