דברי הימים א, פרק א׳, פסוק כ״ט

The expanding family tree of Abraham gradually shifts its focus to detail the lineage of his son Ishmael. The sons are recorded in the exact sequence of their birth, beginning with the firstborn, Nebaioth, followed by Kedar, Adbeel, and Mibsam [ביאור שטיינזלץ].

The total count of these descendants carries a deeper symbolic weight rather than serving as a mere historical record. Together, Ishmael and his sons amount to thirteen individuals, a number that perfectly mirrors the total count of sons born to Keturah. This precise parallel points to the inherent potential within Abraham. Just as he fathered thirteen descendants through his other wives, it would have been fitting for him to establish the tribes of Israel directly through Sarah, as the Israelites themselves ultimately consist of thirteen tribes when the tribe of Levi is counted individually [מלבי״ם].