Proverbs 30:6

Add thou not unto his words, lest he reprove thee, and thou be found a liar.
– Proverbs 30:6

Verse 5 begins the two-part wisdom saying about the reliability of God’s word with the use of covenantal terminology, and verse 6 finishes the saying with a relevant admonition. The first line of the verse echoes the deuteronomistic warning Moses gave the second generation of Israel before entering the Promised Land in Deuteronomy 4:2.

The context of Deuteronomy 4:1-8 informs the intertextual use in Proverbs 30:6. In that context, Moses is rehearsing the covenant to that second generation, emphasizing their need to “hearken” and “do them” in order to possess the land promised to their fathers (Deuteronomy 4:1). They were to keep all of the Lord’s “statutes and … judgments” (Deuteronomy 4:1, 5, 8) without adding to them or taking away from them (Deuteronomy 4:2). Moses even called their keeping and doing of God’s commands “your wisdom and your understanding” (Deuteronomy 4:6). Statutes and judgments corresponds to the plural “words” in Proverbs 30:6, giving the warning not to add the same effect. Moses repeated the warning in Deuteronomy 12:32 and we have it again in another form in Joshua 1:7, where adding or subtracting is depicted through walking off path to the right or left.

The admonition here is about faith and obedience. The saying assures us God’s word cannot be improved. The Pharisees in Jesus’ day were guilty of breaking this command and added and subtracted from God’s word by their own vain traditions (Matthew 15:6; Mark 7:8-9, 13). Agur warned that when God reproves, or judges against his words, violators like the Pharisees will be proved liars. This is exactly what Jesus charged the Pharisees with in John 8:44, 55.