The Scofield Bible Commentary, by Cyrus Ingerson Scofield, [1917], at sacred-texts.com
Genesis Chapter 21
Sarah
Sarah, type of grace, "the freewoman," and of the "Jerusalem which is above." See (Gen 17:15-19); (Gal 4:22-31).
2 Isaac is typical in fourfold way:
(1) of the Church as composed of the spiritual children of Abraham (Gal 4:28).
(2) of Christ as the Son "obedient unto death" (Gen 22:1-10); (Phi 2:5-8).
(3) of Christ as the Bridegroom of a called-out bride see Gen 24; also, "Church," (Mat 16:18);
(See Scofield) - (Mat 16:18).
(4) of the new nature of the believer as "born after the Spirit" (Gal 4:29).
angel
(See Scofield) - (Heb 1:4).
everlasting God
(1) The Hebrew "Olam" is used in Scripture:
(a) of secret or hidden things (for example (Lev 5:2) "hidden"; (Kg2 4:27); "hid"; (Psa 10:1); "hidest");
(b) an indefinite time or age (Lev 25:32); "at any time"; (Jos 24:2) "in old time"). Hence the word is used to express the eternal duration of the being of God, (Psa 90:2). "From everlasting to everlasting"), and is the Hebrew synonym of the Greek "aion," meaning "age" or "dispensation".
(See Scofield) - (Gen 1:26), note (4).
(2) The ideas therefore of things kept secret and of indefinite duration combine in this word. Both ideas inhere in the doctrine of the dispensations or ages. They are among the "mysteries" of God (Eph 1:9); (Eph 1:10); (Eph 3:2-6); (Mat 13:11). The "everlasting" God (El Olam) is therefore that name of Deity in virtue of which He is the God whose wisdom has divided all time and eternity into the mystery of successive ages or dispensations. It is not merely that He is everlasting, but that He is God over everlasting things. See, for other names of Deity:
(See Scofield) - (Gen 1:1).
(See Scofield) - (Gen 2:4).
(See Scofield) - (Gen 2:7).
(See Scofield) - (Gen 14:18
(See Scofield) - (Gen 15:2
(See Scofield) - (Gen 17:1
(See Scofield) - (Sa1 1:3)