What does Genesis 26:16 mean?

Conflict had arisen between Isaac and the Philistines in the region of Gerar. For one thing, they were envious of Isaac's great and growing wealth (Genesis 26:14). Apparently, there were also disputes about water rights. This combination of envy and desperation led the Philistines to begin filling up Isaac's wells with dirt to keep him from using them. Such actions would constitute a direct attack on Isaac's ability to support his vast herds and flocks.

Now the king of the region, Abimelech, steps in to resolve the issue. He's not interested in compromise or working out a treaty in this moment. Abimelech simply tells Isaac to leave. Isaac has become too powerful.

The point Abimelech is making here can be taken in one of two ways. On one hand, Isaac's great estate would require large amounts of land and water. It's possible there just wasn't room in and around the city of Gerar for Isaac's wealth. Abimelech might simply be saying, "your family is more than the land can support." On the other hand, Abimelech might be concerned that Isaac could use his huge number of servants, his money, and the obvious blessing of his God to conquer Abimelech and take over the territory for himself. We're never told Isaac had any inclination to do so, but a king like Abimelech must always be guarding his power and authority.

So Isaac will move away, at least from the main part of Gerar's territory. But he won't move so far as to violate God's command (Genesis 26:2–3). This will result in additional friction with the people. And, as we will see later, it will result in some lingering resentment from Isaac, as well (Genesis 26:26–27).