Deuteronomy 15:9

A thought in thy wicked heart ; literally, a thing in thy heart worthlessness , i . e . a thing which is worthless and unworthy. The word used is belial ( בְּלִיַּעַל ), which does not denote that which is wicked so much as that which is worthless. Thus, "a man of Belial" is a worthless fellow—not necessarily a wicked man (of. Deuteronomy 13:13 ). And it be sin unto thee ; i . e . entail guilt upon thee, and so expose thee to the Divine displeasure.