Charles Ellicott Commentary Genesis 26:18-22

"And Isaac digged again the wells of water, which they had digged in the days of Abraham his father. For the Philistines had stopped them after the death of Abraham. And he called their names after the names by which his father had called them. And Isaac`s servants digged in the valley, and found there a well of springing water. And the herdsmen of Gerar strove with Isaac`s herdsmen, saying, The water is ours. And he called the name of the well Esek, because they contended with him. And they digged another well, and they strove for that also. And he called the name of it Sitnah. And he removed from thence, and digged another well. And for that they strove not. And he called the name of it Rehoboth. And he said, For now Jehovah hath made room for us, and we shall be fruitful in the land." — Genesis 26:18-22 (ASV)

Isaac dug again the wells ... — This activity of Isaac again provoked the opposition of the Philistines. His first well was in the wadi of Gerar and was especially valuable because it was not merely the surface water of a seasonal stream but was fed by a spring, as we learn from its being called a well of living water. However, although Isaac had a right to these wells because of the old covenant between his father and the king, when his claim was resisted, he abandoned the well. As a sign of his displeasure, he called it Esek, contention.

When forced to give up his next well, he called it by a harsher name—Sitnah, enmity; for their opposition was developing into bitter persecution. And so, tired of the conflict, he moved far away, and the Philistines, having achieved their goal, did not follow him any further. Therefore, in peace, he dug another well and called it Rehoboth, wide open spaces.

This well has been identified with one in the wadi Ruhaibeh, now blocked up, but originally twelve feet in diameter and lined with cut stone. It lies south of Beer-sheba, at a distance of eight and one-third leagues, and about forty miles from Gerar.