What does Proverbs 18:9 mean?

Here, Solomon points out that being lazy causes as much disruption as sabotage. Projects, property, and even relationships can be damaged equally through negligence as they can through some deliberate act. In practical ways, this describes someone who fails to maintain a machine, or a building, which eventually causes it to fail. That failure can be just as sudden, and just as harmful, as if the machine or building were deliberately attacked. Carelessness or apathy in a relationship might lead to just as much hurt as deliberate spite.

A person who is lazy on the job robs his employer. Worse, they forget that work should be performed to the glory of God. Colossians 3:17 exhorts, "And whatever you do, in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through him." Also, the same passage teaches workers to obey their earthly masters, "not by way of eye-service, as people-pleasers, but with sincerity of heart, fearing the Lord. Whatever you do, work heartily, as for the Lord and not for men" (Colossians 3:22–23).

The practice of faithfulness applies also to one's Christian service. Instead of slacking off his labor for the Lord, a believer should be "steadfast, immovable, always abounding in the work of the Lord" (1 Corinthians 15:58).