N4 p5 to Ge. 1.28. (A dispensation is a period of time during which man is tested in respect of obedience to some specific revelation of the will of God. Seven such dispensations are distinguished in Scripture. Cmt. on Ge 1:28, note 5.)
N1 p20 to Ge. 12.1. The Fourth Dispensation: Promise. For Abraham and his descendants it is evident that the Abrahamic Covenant (Gen.15.18, note) made a great change. They became distinctively the heirs of promise. That covenant is wholly gracious and unconditional. The descendants of Abraham had but to abide in their own land to inherit every blessing. In Egypt they lost their blessings, but not their covenant. The Dispensation of Promise ended when Israel rashly accepted the law (Ex. 19.8). Grace had prepared a deliverer (Moses), provided a sacrifice for the guilty, and by divine power brought them out of bondage (Ex. 19.4); but at Sinai they exchanged grace for law. The Dispensation of Promise extends from Gen. 12.1 to Ex. 19.8, and was exclusively Israelitish. The dispensation must be distinguished from the covenant. The former is a mode of testing; the latter is everlasting because unconditional. The law did not abrogate the Abrahamic Covenant (Gal. 3.15-18), but was an intermediate disciplinary dealing ‘till the Seed should come to whom the promise was made’ (Gal. 3.19-29; 4.1-7). Only the dispensation, as a testing of Israel, ended at the giving of the law.
See, for the other dispensations: Innocence (Gen. 1.28); Conscience (Gen. 3.23); Human Government (Gen. 8.20); Law (Ex. 19.8); Grace (John 1.17); Kingdom (Eph. 1.10).
Ga. 4.19-31 (The two systems, law and grace cannot co-exist.).
N1 p1246 to Ga. 4.19 “My little children, of whom I travail in birth again until Christ be formed in you,” “The allegory Ga 4:22-31 is addressed to justified but immature believers (cf) 1Co 3:1-2 who, under the influence of legalistic teachers, “desire to be under the law,” and has, therefore, no application to a sinner seeking justification. It raises and answers, for the fifth time in this Epistle, the question, Is the believer under the law? Ga 2:19-21; 3:1-3,25; 4:4-6,9-31.”
Ga. 4.19-30. “… 28 Now we, brethren, as Isaac was, are the children of promise. 29 But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now. 30 Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman. 31 So then, brethren, we are not children of the bondwoman, but of the free.”