Here we have a testimonial as to the Divine origin of the Torah. No human writer would have attributed the Ishmaelite nations to Avrohom. At most, he would perhaps have given them lineage from a brother of Avrohom. The fact that the Torah openly declares that Yishmoel was born to Avrohom is clear evidence that no human author composed the Torah. From the days of Moshe the Ishmaelite nations were idolators and enemies of Am Yisroel. It would therefore be unthinkable that any Jewish author would confer upon them the pedigree of descent from the hallowed Father of our Nation. It is also a testimonial to the truthfulness of the Torah-nation, for never was a single copy of the Torah altered to conceal this fact of Yishmoel’s lineage. Such damaging truths are numerous in the Torah. Each one serves as a testimonial to the divine origin of the Torah, and to the truthfulness of the Torah-nation that did not alter the text.