Jeremiah 2:5
Thus saith the LORD, What iniquity have your fathers found in me, that they are gone far from me, and have walked after vanity, and are become vain? Thus saith the LORD, What iniquity have your fathers found in me, that they are gone far from me, and have walked after vanity, and are become vain?
The Lord puts a searching question to His people about what fault or injustice their forefathers had discovered in Him that caused them to move far away from Him. To walk after vanity is to follow after that which is empty and worthless, and to become vain is to become empty and worthless in character through that pursuit. The inquiry looks back to Israel's earlier faithfulness and sets it in contrast with later generations who did not gain wisdom from that example.