What does Genesis 25:6 mean?

The previous verse was clear that Abraham gave all his great wealth to Isaac (Genesis 25:1–5). In addition, God's covenant promises were established with Isaac, as well. He was the child of the promise. It was Abraham's line through Isaac that would result in God's chosen people Israel and, eventually, lead to Christ Himself.

However, Abraham did not leave his sons by his concubines empty handed. Though never referred to as a "concubine" exactly, it's possible that this includes Hagar (Genesis 16:1–3). Abraham showed great affection for Ishmael, his son by Hagar, and Ishmael will participate in Abraham's burial in the following verses. Keturah, Abraham's "other wife" after Sarah, is referred to as a concubine in 1 Chronicles 1:32. We're not told of any other women who would have been considered Abraham's concubines.

In any case, before Abraham died he gave gifts, probably from his vast wealth, to each of these sons and sent them away from Isaac. Abraham was intent that Isaac remain in the promised land of Canaan and that there be no confusion, even after his death, about exactly who Abraham's sole heir was. To that end, Abraham sent all of these other sons away to the desert regions east of what would later become Israel.