Al Khazneh Firoun (Treasury of the Pharaoh), Nabatean architecture- Petra, Jordan. The Nabateans descend from Hajar through Ishmael.
According to the Midrash (Gen. R. xlv.), Hagar was the daughter of Pharaoh, who, seeing what great miracles God had done for Sarah’s sake (Gen. xii. 17), said: “It is better for Hagar to be a slave in Sarah’s house than mistress in her own.” In this sense Hagar’s name is interpreted as “reward” (“Ha-Agar” = “this is reward”). She was at first reluctant when Sarah desired her to marry Abraham, and although Sarah had full authority over her as her handmaid, she persuaded her, saying. “Consider thyself happy to be united with this saint.” Hagar is held up as an example of the high degree of godliness prevalent in Abraham’s time, for while Manoah was afraid that he would die because he had seen an angel of God (Judges xiii. 22), Hagar was not frightened by the sight of the divine messenger (Gen. R.l.c.). Her fidelity is praised, for even after Abraham sent her away she kept her marriage vow, and therefore she was identified with Keturah (Gen. xxv.1), with allusion to (Aramaic, “to tie”; Gen. R. lxi.). Another explanation of the same name is “to adorn,” because she was adorned with piety and good deeds (l.c.). It was Isaac who, after the death of Sarah, went to bring back Hagar to the house of his father; the Rabbis infer this from the report that Isaac came from Beer-lahai-roi, the place which Hagar had named (Gen. xvi. 14, xxiv. 62; Gen. R. lx.; see commentaries ad loc.). Source: Jewish Encyclopedia
After Ishmael came of age, Hājar returned to Egypt with her son, who was the grandson of the Pharaoh, and married him to an Egyptian woman.
Gen 21:20 And God was with the lad; and he grew, and dwelt in the wilderness, and became an archer.
Gen 21:21 And he dwelt in the wilderness of Paran: and his mother took him a wife out of the land of Egypt.
Qasr al-Bint Firoun (Palace of the Daughter of the Pharaoh), Petra, Jordan