For it is written - Genesis 16; 21.

Abraham had two sons - Ishmael and Isaac. Abraham subsequently had several sons by Keturah after the death of Sarah; Genesis 26:1-6. But the two sons by Hagar and Sarah were the most prominent, and the events of their lives furnished the particular illustration which Paul desired.

The one by a bond-maid - Ishmael, the son of Hagar. Hagar was an Egyptian slave, whom Sarah gave to Abraham in order that he might not be wholly without posterity; Genesis 16:3.

The other by a free woman - Isaac, the son of Sarah; Genesis 21:1-2.

For it is written - Viz. in Genesis 16:15; Genesis 22:1, etc., that Abraham had two sons, Ishmael and Isaac; the one; Ishmael, by a bond maid, Hagar; the other, Isaac, by a free woman, Sarah.

For it is written,.... In Genesis 16:15

that Abraham had two sons, not two sons only; for besides the two referred to, he had six more, Genesis 25:2 but it being only pertinent to the apostle's purpose to take notice of these two, he mentions no more, though he does not deny that he had any more. These two sons were Ishmael and Isaac:

the one by a bondmaid. Ishmael was by Hagar, Sarah's servant, who represented the covenant the Jewish nation was under the bondage of.

The other by a free woman. Isaac was by Sarah, Abraham's proper and lawful wife, who was mistress of the family, and represented in figure the covenant, and Gospel church state, and all believers, Gentiles as well as Jews, as under the liberty thereof.

For (γάρ)

Your determination to be under the law is opposed by Scripture, if you will understand it, for it is written, etc.

A bondmaid (τῆς παιδίσκης)

The bondmaid, indicating a well known character, Hagar, Genesis 16:3. The word in Class. means also a free maiden; but in N.T. always a slave. So almost always in lxx; but see Ruth 4:12; Judith 12:13.

For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman.

4:22 Abraham had two sons, the one by a bondmaid. Hagar, whose child was Ishmael (Ge 16:15).

The other by a freewoman. Sarah, whose child was Isaac (Ge 21:3).

4:22 Gen 21:2,9.

22. (Ge 16:3-16; 21:2).

Abraham-whose sons ye wish to be (compare Ro 9:7-9).

a bond maid . a free woman-rather, as Greek, "the bond maid . the free woman."

4:21-27 The difference between believers who rested in Christ only, and those who trusted in the law, is explained by the histories of Isaac and Ishmael. These things are an allegory, wherein, beside the literal and historical sense of the words, the Spirit of God points out something further. Hagar and Sarah were apt emblems of the two different dispensations of the covenant. The heavenly Jerusalem, the true church from above, represented by Sarah, is in a state of freedom, and is the mother of all believers, who are born of the Holy Spirit. They were by regeneration and true faith, made a part of the true seed of Abraham, according to the promise made to him.