He surrendered His people to the sword because He was enraged by His heritage.
PSALM 78 To comprehend many things within small compass, it is to be observed, that in this psalm there are two leading topics. On the one hand, it is declared how God adopted for himself a Church from the posterity of Abraham, how tenderly and graciously he cherished it, how wonderfully he brought it out of Egypt, and how varied were the blessings which he bestowed upon it.
Commenting on Psalm 78:1-72
He gave his people over also unto the sword. They fell in battle because they were no longer aided by the divine strength. Sharp was the sword, but sharper still the cause of its being unsheathed. And was wroth with his inheritance.
The matter and scope of this paragraph are the same with the former, showing what great mercies God had bestowed upon Israel, how provoking they had been, what judgments he had brought upon them for their sins, and yet how, in judgment, he remembered mercy at last.
Commenting on Psalm 78:40-72