David is singing Psalm 21 to give thanks for what he has learned from experience. The Lord had him write down His experience so we could also learn from it. It is always nice to hear someone give their testimony about what the Lord has done for them. Since the Lord is no respecter of person, I can expect the Lord to do the same thing for me. In verse eight, David lets us know that the Lord will search out and expose our enemies. Sometimes it is hard to discern if someone is for me or against me. David found out not only will the Lord expose our enemies but He will also destroy their plans. When David uses the illustration of the fiery furnace, I wonder if this is the verse the three Hebrew children in the Book of Daniel stood on when they were tied and thrown into a furnace that was red hot with fire. Remember, the story explained they were not hurt but all of the guards were burned alive. God will protect His people! Verse eleven is anotherverse that you and I need to say “I will take that”. It explains to us that the evil one will make up plots and strategies and weapons but he will not be able to pull it off. That is good news and confirms what Isaiah 54:17 states that no weapon will prosper against us. Ephesians 6:16 also states the shield of faith will stop all the missiles that the enemy shoots against us. The Psalm finishes with a warning to the Devil that the Lord has His bow drawn and ready to fire so he had better stop picking on the Lord’s kids. It is great to know that we have a Big Brother, Jesus, who is on our side and is ready to fight for us and He has already overcome the evil one. No wonder David said he was singing praise to the power of the Lord.
(Psa 21:11 NLT) Although they plot against you, their evil schemes will never succeed.