Here is a small passage about the later life of Abraham. After Sarah died, Abraham took another wife, Keturah. This is an obscure story, but one that merits some attention. Keturah bore several sons, some of whom would become nations that Israel would eventually fight in battle, especially Midian. If you notice the details of this account, you see that Isaac got all the inheritance, but the other sons got gifts and were sent East. Practically all the nations that now even fight against Israel are to the East of Israel.
This is just one more example of how it is possible to get ahead of God. God promised Abraham a son from Sarah that would be the father of a great nation. His foray with Hagar was the first mistake, producing Ishmael. Now, his later marriage to Keturah produced even more enemies to the promised nation. We must be careful not to do less or more than what God has ordained for us. When we hear His voice and obey Him, the blessings come. When we run ahead or lag behind, we run alone!