According to their pasture, so were they filled; they were filled, and their heart was exalted; therefore have they forgotten me.

Wesley's Notes

13:6 Their pasture - When they were come into Canaan, and had abundance of all things, they ran into luxury. Was exalted - They grew proud.

Jamieson-Fausset-Brown Bible Commentary

6. Image from cattle, waxing wanton in abundant pasture (compare Ho 2:5, 8; De 32:13-15). In proportion as I fed them to the full, they were so satiated that "their heart was exalted"; a sad contrast to the time when, by God's blessing, Ephraim truly "exalted himself in Israel" (Ho 13:1).

therefore have they forgotten me-the very reason why men should remember God (namely, prosperity, which comes from Him) is the cause often of their forgetting Him. God had warned them of this danger (De 6:11, 12).

Matthew Henry's Concise Commentary

13:1-8 While Ephraim kept up a holy fear of God, and worshipped Him in that fear, so long he was very considerable. When Ephraim forsook God, and followed idolatry, he sunk. Let the men that sacrifice kiss the calves, in token of their adoration of them, affection for them, and obedience to them; but the Lord will not give his glory to another, and therefore all that worship images shall be confounded. No solid, lasting comfort, is to be expected any where but in God. God not only took care of the Israelites in the wilderness, he put them in possession of Canaan, a good land; but worldly prosperity, when it feeds men's pride, makes them forgetful of God. Therefore the Lord would meet them in just vengeance, as the most terrible beast that inhabited their forests. Abused goodness calls for greater severity.