איוב כ:יח פירוש: רש״י

He will return that which he labored for The loot that he stole.

when his gain becomes vast wealth When his gain becomes vast wealth, then he will lose it.

he will not rejoice Heb. יעלס, with it. Similarly, יַעֲלֹז, and so יַעַלֹץ ; the three of them are interchangeable.