The Weaning of Isaac
The Start of the 400 Years of Affliction
God promised Abraham that he and his posterity would live for four centuries in a land that was not theirs and that they would be afflicted for 400 years.
Now when the sun was going down, a deep sleep fell upon Abram; and behold, horror and great darkness fell upon him. Then He said to Abram: “Know certainly that your descendants will be strangers in a land that is not theirs, and will serve them, and they will afflict them four hundred years. And also the nation whom they serve I will judge; afterward they shall come out with great possessions. Now as for you, you shall go to your fathers in peace; you shall be buried at a good old age. But in the fourth generation they shall return here, for the iniquity of the Amorites is not yet complete.” (Genesis 15:12-16)
Bible scholars disagree about when the four centuries of affliction began. Bishop James Ussher argued that the era of affliction began with Isaac’s weaning at about age 5.
Abraham was born in 1996 BC. When his father died God commanded him to go to Canaan. He crossed the Euphrates and went down to Egypt in the same year as God’s first promise to him in 1921 BC when Abraham was 75 years old.
Twenty-five years later in 1896 BC, Isaac, the son of the promise, was born when Abraham was 100 years old. Five years later, about 1891 BC, two things happened that indicated the start of the four centuries of affliction.
The Mocking of Isaac
First, when Isaac was weaned, his older half-brother, Ishmael, the son of the Egyptian woman, mocked him.
So the child grew and was weaned. And Abraham made a great feast on the same day that Isaac was weaned. And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing. Therefore she said to Abraham, “Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, namely with Isaac.” (Genesis 21:8-10)
Ishmael was 13 years old when Abraham was circumcised at the age of 99. Therefore, if Isaac was weaned at age 5, Ishmael was about 19. It seems strange that Genesis would refer to Ishmael as a “child” when Hagar took him away. However, the evidence in Genesis suggests that the age of sexual maturity for men and women slowly declined from about age 30 just after the Flood. It took about a thousand years for the average life expectancy and age of sexual maturity to reach their present values.
When Isaac was born, the age of sexual maturity was about 25 years. Therefore a 19-year-old boy in 1891 BC would have had the body of a nine-year-old boy today. This also explains why Isaac was weaned around the age of five when children today usually wean themselves before the age of two. It simply took twice as long for children to reach adult size and sexual maturity.
Ishmael’s mocking of Isaac got him kicked out of Abraham’s household. Symbolically, this represented the beginning of the 400 years of affliction under the house of Mizraim, the father of both the Philistines and the Egyptians.
Abimelech’s Authority Over Abraham
The second event recorded in Genesis 21 is that the men of Abimelech stopped up Abraham’s wells, and then Abimelech forced Abraham to take a covenant oath to him.
So Abraham took sheep and oxen and gave them to Abimelech, and the two of them made a covenant. And Abraham set seven ewe lambs of the flock by themselves.
Then Abimelech asked Abraham, “What is the meaning of these seven ewe lambs which you have set by themselves?”
And he said, “You will take these seven ewe lambs from my hand, that they may be my witness that I have dug this well.” Therefore he called that place Beersheba, because the two of them swore an oath there.
In the Ancient Near East, a “covenant” was a treaty made between a Great King and his Vassal. The fact that Abraham gave the lambs to Abimelech meant that Abraham was the subordinate in the covenant. Thus the four centuries of affliction under the rule of “another nation” began with Abraham’s covenant with Abimelech. That other nation was Mizraim, the father of both the Philistines and the Egyptians.
Conclusion
Two events in Genesis 21 marked the start of the four centuries of affliction: the mocking of Isaac and Abraham’s covenant under Abimelech. That covenant was made in the year 1891 BC. The Exodus from Egypt would occur exactly 400 years later in 1491 BC.