What does Psalm 35:18 mean?

David promises to thank the Lord publicly for delivering him from his enemies. The "great congregation" and "the mighty throng" seem to refer to the assembly of worshipers in the tabernacle. David's first act of praising the Lord would be private (Psalm 35:9–10). Proper worship naturally begins in a person's innermost thoughts and motivations, then expresses itself outwardly. So, David's second act of praise would be public; in fact, he would make a point of celebrating God's goodness among others.

Praise ought to be both private and public. A believer should thank the Lord daily for His many blessings. Also, if opportunity presents itself, he should praise God when his fellow Christians gather for worship. In 1 Thessalonians 5:18 Paul admonishes the believers at Thessalonica to "give thanks in all circumstances; for this is the will of God in Christ Jesus." A Christian often seeks to know God's will for his life, and one aspect of the Lord's will is clear in 1 Thessalonians 5:18. He wants every believer to give thanks.