Figuratively, fatness means abundance; specifically, the word refers to the (fatty) ashes of sacrifices (Strong). Thus, the fatness of God’s house comes from the sacrifices, the offerings, all of which typify the all-inclusive Christ (Heb. 10:5-10). The fatness of God’s house, therefore, refers to the riches of Christ (Eph. 3:8). The fatty ashes of the offerings are the signs of Christ’s accomplishment through His death (cf. note Lev. 4:121 and note Lev. 6:101 ).
Verses 8-9 reveal the Divine Trinity in His divine dispensing as the enjoyment of God’s people in His house. The fatness refers to Christ, the Son; the river of the divine pleasures, to the Spirit as the river of water of life (John 7:37-39; Rev. 22:1); and the fountain of life and light (v. 9), to the Father as the source of life and light (John 1:4; 1 John 1:5; Rev. 21:23; 22:1-2, 5). These verses indicate that even in the dispensation of law, before the dispensation of grace in the New Testament age, the seeking saints enjoyed the Triune God in His dwelling place on earth. They indicate further that the entire Bible was written according to the controlling vision that the Triune God is working Himself into His chosen and redeemed people to be their life and life supply in order to saturate their entire being with the Divine Trinity, that is, with the Father as the fountain, the Son as the fatness, and the Spirit as the river.