Exodus 17:8

Then came Amalek, and fought with Israel - The Amalekites seem to have attacked the Israelites in the same way and through the same motives that the wandering Arabs attack the caravans which annually pass through the same desert. It does not appear that the Israelites gave them any kind of provocation, they seem to have attacked them merely through the hopes of plunder. The Amalekites were the posterity of Amalek, one of the dukes of Eliphaz, the son of Esau, and consequently Israel's brother, Genesis 36:15, Genesis 36:16.

Fought with Israel - In the most treacherous and dastardly manner; for they came at the rear of the camp, smote the hindmost of the people, even all that were feeble behind, when they were faint and weary; see Deuteronomy 25:18. The baggage, no doubt, was the object of their avarice; but finding the women, children, aged and infirm persons, behind with the baggage, they smote them and took away their spoils.

Then came Amalek - The attack occurred about two months after the Exodus, toward the end of May or early in June, when the Bedouins leave the lower plains in order to find pasture for their flocks on the cooler heights. The approach of the Israelites to Sinai would of course attract notice, and no cause of warfare is more common than a dispute for the right of pasturage. The Amalekites were at that time the most powerful race in the Peninsula; here they took their position as the chief of the pagans. They were also the first among the pagans who attacked God's people, and as such were marked out for punishment (see the marginal references).

17:8 Then Amalek came and fought with Israel - The Amalekites were the posterity of Esau, who hated Jacob because of the birth - right and blessing. They did not boldly front them as a generous enemy, but without any provocation given, basely fell upon their rear, and smote them that were faint and feeble.