Let not him that is deceived trust in vanity - The sense is, “Let him not trust in vanity. He will be deceived. Vanity will be his recompense.” The idea is, that a man should not confide in that which will furnish no support. He should not rely on his wealth and rank; his houses and lands; his servants, his armies, or his power, if he is wicked, for all this is vain. He needs some better reliance, and that can be found only in a righteous life. The word vanity here means that which is unsubstantial; which cannot uphold or sustain; which will certainly give way.
For vanity will be his recompense - He will find only vanity. He will be stripped of all his honors and possessions.