“A sense of God’s relation to us as a Father, is necessary to this delight [ie. prayer]. We may use other titles and appellations of God, but as a Father he is the ultimate object of all evangelical worship, of all our prayers: so it is expressed in that holy and divine description of it, given us by the apostle, “Through Christ we have access by the Spirit to the Father’ (Eph 2:18). No tongue can express, no mind can reach the heavenly placidness and soul – satisfying sweetness which are intimated in these words. Without a due apprehension of God in this relation, no man can pray as he ought; and we can have no sense hereof but by the Holy Ghost, who ‘bears witness with our spirits, that we are the children of God’ (Rom 8:16).”
John Owen, The Holy Spirit, 358.