H1891. habal
הָבַל verb denominative act emptily, become vain —
Qal [Jer 2:5] = [2Kin 17:15] they went after vanity וַיֶּהְבָּ֑לוּ and became vain, [Psa 62:11] אַלתֶּֿהְבָּ֑לוּ וּבְגָזֵל do not become vain (i.e. be demoralized) by robbery; with cognate accusative [Job 27:12] תֶּהְבָּ֑לוּ הֶבֶל זֶה לָמָּה why do ye become vain with vanity (i.e. shew yourselves utterly vain) ?
Hiph`il cause to become vain [Jer 23:16] (of false prophets) אֶתְכֶם הֵמָּה מַהְבִּלִים i.e. fill you with vain hopes.