The Holy Scriptures have recorded many incidents of Bible History in which an early event was symbolic of a later event, sometimes so with inverted circumstances from the original. Hagar, the Egyptian maid of Abraham and Sarah is one such example.
The birth of Sarah's son Isaac:
"21:1 And the LORD [see 'Before Abraham Was, I AM'] visited Sarah as he had said, and the LORD did unto Sarah as he had spoken. 21:2 For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. 21:3 And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac. 21:4 And Abraham circumcised [see Circumcision] his son Isaac being eight days old, as God had commanded him. 21:5 And Abraham was an hundred years old, when his son Isaac was born unto him. 21:6 And Sarah said, God hath made me to laugh, so that all that hear will laugh with me. 21:7 And she said, Who would have said unto Abraham, that Sarah should have given children suck? for I have born him a son in his old age. 21:8 And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned." (Genesis 21:1-8 KJV)
Hagar "answereth to Jerusalem which now is, and is in bondage with her children"
The strife between Sarah and Hagar was the result of their children. While under the impression that she could not have children of her own, Sarah arranged to have Hagar become a surrogate mother with Abraham - from which Hagar gave birth to Abraham's son Ishmael. Later however, Sarah became a mother herself with the birth of Abraham's son Isaac. After that, Sarah had Hagar and her son sent away.
"21:9 And Sarah saw the son of Hagar the Egyptian, which she had born unto Abraham, mocking.
21:10 Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac.
21:11 And the thing was very grievous in Abraham's sight because of his son.
21:12 And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called. 21:13 And also of the son of the bondwoman will I make a nation, because he is thy seed.
21:14 And Abraham rose up early in the morning, and took bread, and a bottle of water, and gave it unto Hagar, putting it on her shoulder, and the child, and sent her away: and she departed, and wandered in the wilderness of Beersheba.
21:15 And the water was spent in the bottle, and she cast the child under one of the shrubs.
21:16 And she went, and sat her down over against him a good way off, as it were a bowshot: for she said, Let me not see the death of the child. And she sat over against him, and lift up her voice, and wept.
21:17 And God heard the voice of the lad; and the angel of God called to Hagar out of heaven, and said unto her, What aileth thee, Hagar? fear not; for God hath heard the voice of the lad where he is.
21:18 Arise, lift up the lad, and hold him in thine hand; for I will make him a great nation.
21:19 And God opened her eyes, and she saw a well of water; and she went, and filled the bottle with water, and gave the lad drink.
21:20 And God was with the lad; and he grew, and dwelt in the wilderness, and became an archer.
21:21 And he dwelt in the wilderness of Paran: and his mother took him a wife out of the land of Egypt." (Genesis 21:1-21 KJV)
From the perspective of Israelite history, Sarah was the free woman, while Hagar was in bondage. But consider what the apostle Paul says about "Jerusalem" (i.e. the as-yet unconverted people of Judah) today - they are Hagar/Agar: "For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children" (Galatians 4:25 KJV). Why? Because they have taken the Law of God, which was given to man to set man free from human nature (but not from God's Law itself - see Grace Into Licentiousness) and made it into a burden. The Messiah himself, who they accused of being a "sinner" (see Did Jesus Break The Law?) plainly stated it:
"23:1 Then spake Jesus to the multitude, and to his disciples, 23:2 Saying, The scribes and the Pharisees sit in Moses' seat: 23:3 All therefore whatsoever they bid you observe, that observe and do; but do not ye after their works: for they say, and do not. 23:4 For they bind heavy burdens and grievous to be borne, and lay them on men's shoulders; but they themselves will not move them with one of their fingers.
23:5 But all their works they do for to be seen of men: they make broad their phylacteries [see Frontlets and Phylacteries], and enlarge the borders of their garments, 23:6 And love the uppermost rooms at feasts, and the chief seats in the synagogues, 23:7 And greetings in the markets, and to be called of men, Rabbi, Rabbi.
23:8 But be not ye called Rabbi: for one is your Master, even Christ; and all ye are brethren.
23:9 And call no man your father upon the earth: for one is your Father, which is in heaven.
23:10 Neither be ye called masters: for one is your Master, even Christ. 23:11 But he that is greatest among you shall be your servant. 23:12 And whosoever shall exalt himself shall be abased; and he that shall humble himself shall be exalted.
23:13 But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in yourselves, neither suffer ye them that are entering to go in.
23:14 Woe unto you, scribes and Pharisees, hypocrites! for ye devour widows' houses, and for a pretence make long prayer: therefore ye shall receive the greater damnation." (Matthew 23:1-14 KJV)
The apostle Paul (see Paul's Ministry) plainly made the connection between Hagar / Agar and the as-yet unconverted people of Judah today (the significance of "childless" Sarah later having a child of her own after Hagar, the woman in bondage, had a child for her is at least partly symbolic of the coming conversion of the people of Judah as a whole - see Why Can't 'The Chosen People' See?):
"4:22 For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman. 4:23 But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise.
4:24 Which things are an allegory: for these are the two covenants [see Covenant and Testament]; the one from the mount Sinai, which gendereth to bondage, which is Agar [note: the King James Version renders her name "Hagar" in the Old Testament and "Agar" in the New Testament]. 4:25 For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is [see Sodom and Egypt], and is in bondage with her children. 4:26 But Jerusalem which is above is free, which is the mother of us all. 4:27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband.
4:28 Now we, brethren, as Isaac was, are the children of promise. 4:29 But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now.
4:30 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. 4:31 So then, brethren, we are not children of the bondwoman, but of the free." (Galatians 4:22-32 KJV)
Fact Finder: Paul's statement "mount Sinai in Arabia" has caused some to incorrectly believe that Mount Sinai was in (Saudi) Arabia rather than the Sinai Peninisula. Why did Paul say what he did?
See Why Did Paul Say That Sinai Was In Arabia?