They tested God in their heart by demanding the food they craved.
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
And they tempted God in their heart. He was not tempted, for he cannot be tempted by any, but they acted in a manner calculated to tempt him, and it always just to charge that upon men which is the obvious tendency of their conduct.
In these verses, I. The psalmist observes the late rebukes of Providence that the people of Israel had been under, which they had brought upon themselves by their dealing treacherously with God, Psa 78:9-11. The children of Ephraim, in which tribe Shiloh was, though they were well armed and shot with bows, yet turned back in the day of battle.
Commenting on Psalm 78:9-39