Judges 2:22

That through them I may prove Israel, whether they will keep the way of the Lord to walk therein, as their fathers did keep it, or not.

Cross-reference

Judges 3:1-4 lists the nations God left to test Israel, directly fulfilling the test mentioned here.

Judges 3:4 restates the same purpose almost verbatim — to test whether Israel would obey the Lord's commands.

Deuteronomy 8:2 uses nearly identical language: God tested Israel in the wilderness 'to know what was in your heart'.

Deuteronomy 13:3 says God tests loyalty through false prophets — same testing motif.