What does Proverbs 20:10 mean?

Because God is holy and righteous, He detests sin, which includes theft and dishonesty (Exodus 20:15; Proverbs 6:16–19). An example of both is cheating in business, here portrayed as the use of deceptive measurements. In the ancient world, this could involve using two different sets of weights, while pretending they were the same. A crooked vendor might agree to trade a certain weight of grain for a certain weight of gold, using these modified balances to secretly cheat a customer. The Hebrew phrase literally says something like "weights and weights, measures and measures," calling such things despicable in God's eyes.

Cheating in business has always been a temptation for mankind; it's one clear example of the charge made in verse 9 that no one is pure and clean from sin (Proverbs 20:9). This can involve literal weights, as when a dishonest butcher presses on the scale with his thumb to gain a bigger payment for his meat—but the Lord sees the thumb (Hebrews 4:13). It also applies to any form of deception, whether it relies on physical tricks or corrupt record-keeping. The Lord always sees the transaction. No one can cheat in business and escape God's notice and judgment. All dishonest transactions are an "abomination" to Him.

The same sentiment is repeated in verse 23, with additional emphasis on using deceptive scales (Proverbs 20:23).