C. F. Keil and Franz Delitzsch on 1 Chronicles 1:29-33

1Ch 1:29-33

The names of the generations (תּולדות) of Ishmael (Hebr. Yishma'el) correspond to those in Gen 25:12-15, and have been there explained. In 1Ch 1:32. also, the names of the thirteen descendants of Abraham by Keturah, six sons and seven grandsons, agree with Gen 25:1-4 (see commentary on that passage); only the tribes mentioned in Gen 25:3, which were descended from Dedan the grandson of Keturah, are omitted. From this Bertheau wrongly concludes that the chronicler probably did not find these names in his copy of the Pentateuch. The reason of the omission is rather this, that in Genesis the great-grandchildren are not themselves mentioned, but only the tribes descended from the grandchildren, while the chronicler wished to enumerate only the sons and grandsons. Keturah is called פּילגשׁ after Gen 25:6, where Keturah and Hagar are so named.