And Abraham reproved Abimelech because of a well of water, which Abimelech's servants had violently taken away.

Jamieson-Fausset-Brown Bible Commentary

25-31. And Abraham reproved Abimelech because of a well-Wells were of great importance to a pastoral chief and on the successful operation of sinking a new one, the owner was solemnly informed in person. If, however, they were allowed to get out of repair, the restorer acquired a right to them. In unoccupied lands the possession of wells gave a right of property in the land, and dread of this had caused the offense for which Abraham reproved Abimelech. Some describe four, others five, wells in Beer-sheba.

Matthew Henry's Concise Commentary

21:22-34 Abimelech felt sure that the promises of God would be fulfilled to Abraham. It is wise to connect ourselves with those who are blessed of God; and we ought to requite kindness to those who have been kind to us. Wells of water are scarce and valuable in eastern countries. Abraham took care to have his title to the well allowed, to prevent disputes in future. No more can be expected from an honest man than that he be ready to do right, as soon as he knows he has done wrong. Abraham, being now in a good neighbourhood, stayed a great while there. There he made, not only a constant practice, but an open profession of his religion. There he called on the name of the Lord, as the everlasting God; probably in the grove he planted, which was his place of prayer. Abraham kept up public worship, in which his neighbours might join. Good men should do all they can to make others so. Wherever we sojourn, we must neither neglect nor be ashamed of the worship of Jehovah.