Here are some excerpts from Swedenborg's "Arcana Coelestia" that help explain the inner meaning of this chapter:

AC 2610. In the internal sense of this chapter the Lord‘s Divine Rational is first treated of, which is represented by "Isaac" (verses 1-8).

AC 2611. Next the merely human rational, which was then separated, and which is the "son of Hagar the Egyptian" (verses 9-12).

AC 2612. After this had been separated, the spiritual church is represented by the same, namely, by Hagar’s son, as well as by his mother; which church and its state are treated of in (verses 13 to 21).

AC 2613. Concerning the human rational things that were adjoined to the doctrine of faith, which in itself is Divine (verses 22-34).

AC 2614. This doctrine together with those things adjoined is "Beer-sheba" (verses 14, 31, 33).

2498. THE INTERNAL SENSE

These historical descriptions, like everything else in the Word, embody Divine arcana. This becomes clear from the fact that now, for a second time, Abraham said that his wife was his sister; for the same thing had happened when he entered Egypt. On that occasion he said to Sarah, 'Say, now, you are my sister', Genesis 12:13. And not only Abraham but also Isaac did so, in that when he came to Gerar he said that Rebekah his wife was his sister - 'The men of the place asked about his wife, and he said, She is my sister', Genesis 26:6-7. And in those two chapters further similarities occur, so that such historical incidents are described three times, which would never have been done but for some hidden reason in the internal sense.