On what basis did the shepherds of Gerar lay claim to the wells that Yitzchak now dug?
Malbim #1: They claimed that the source of the "Mayim Chayim" was the mountain in Gerar, within Avimelech's domain.
Malbim #2: The kingdom had a law that anything found in the ground belongs to the kingdom. Yitzchak's shepherds said that what is in the ground is Hefker; since they dug and found it, it is theirs.
Oznayim la'Torah: Normally, when someone begins digging a well to which he has no right, one stops him in his tracks. But when a Jew begins digging a well to which he has no right, one lets him finish it - and then calls him a thief and confiscates it.
Seeing as the Pelishtim quarreled over both the first and the second wells, what is the difference between the connotations of the names 'Esek' and 'Sitnah'? How do the names reflect the interactions between Yitzchak and shepherds of Gerar?
Ramban: 'Sitnah' has connotations of a more intense quarrel than 'Esek.'
Targum Yonasan: In the case of 'Esek,' the Pelishtim took over the well, and it dried up, so they returned it to Yitzchak, and it flowed again. They took 'Sitnah,' and it did not flow again. 1
Hadar Zekenim: At first, Yitzchak thought that they just happened to quarrel. After the second time, he realized that it was based on hatred.
Malbim #1: The shepherds of Gerar had a claim to the first well, which was Mayim Chayim (refer to 26:20:1). The second well was from rain water, which is Hefker. They quarreled about it without any claim.
Malbim #2: The shepherds of Gerar quarreled about the first well because they needed water. It was Mayim Chayim, which does not cease; they did not need another well. They quarreled about the second well only amidst hatred, to cause a loss to Yitzchak.
Ha'amek Davar: There was a debate about the first well - whether it took water from the river, or was Mayim Chayim. The nobles, amidst hatred, allowed the shepherds of Gerar to take it via a false claim. After this success, they stole to the second well without any claim.
Gur Aryeh: The first well was close to the valley. The shepherds claimed (Esek) that the well merely drew out water from the stream, and they confiscated the well. Yitzchak then dug a second well, just far enough that they could not claim this. Yet they remained his adversaries (Sitnah), saying, 'We would have dug here, had you not done so first!' Yitzchak then moved to a different area, where they could not claim that they would have come; and so they had neither claim nor quarrel. This well he named Rechovos.
Why did they quarrel with Yitzchak? There was a covenant between Avraham and Avimelech for three generations!