'Vain' in the Bible

And they rejected his statutes, and his covenant that he made with their fathers, and his testimonies which he testified against them; and they followed vanity, and became vain, and went after the heathen that were round about them, concerning whom the LORD had charged them, that they should not do like them.

Thou sayest, (but they are but vain words,) I have counsel and strength for the war. Now on whom dost thou trust, that thou rebellest against me?