2 Kings 17:38

And the covenant that I have made with you ye shall not forget; neither shall ye fear other gods.

Cross-reference

In Deuteronomy 4:23, the same warning not to forget the covenant is tied to the prohibition of idols — reinforcing 2 Kings 17:38's command.

In Deuteronomy 6:12, forgetting the LORD leads to abandoning him — the same danger behind 2 Kings 17:38's command not to forget the covenant.

In Deuteronomy 8:14-18, prosperity can cause forgetfulness of God — mirroring 2 Kings 17:38's warning against forgetting the covenant.