30. grieve not--A condescension to human modes of thought most touching. Compare "vexed His Holy Spirit" (Isa 63:10; Ps 78:40); "fretted me" (Eze 16:43: implying His tender love to us); and of hardened unbelievers, "resist the Holy Ghost" (Ac 7:51). This verse refers to believers, who grieve the Spirit by inconsistencies such as in the context are spoken of, corrupt or worthless conversation, &c.
      whereby ye are sealed--rather, "wherein (or 'in whom') ye were sealed." As in Eph 1:13, believers are said to be sealed "in" Christ, so here "in the Holy Spirit," who is one with Christ, and who reveals Christ in the soul: the Greek implies that the sealing was done already once for all. It is the Father "BY" whom believers, as well as the Son Himself, were sealed (Joh 6:27). The Spirit is represented as itself the seal (Eph 1:13, for the image employed, see on Eph 1:13). Here the Spirit is the element IN which the believer is sealed, His gracious influences being the seal itself.
      unto--kept safely against the day of redemption, namely, of the completion of redemption in the deliverance of the body as well as the soul from all sin and sorrow (Eph 1:14; Lu 21:28; Ro 8:23).

JFB.