Just an instrument: Boast not
“Shall the ax boast itself against him who chops with it?” Isaiah 10:15
It's a blessing and a privilege to be used by God. Nevertheless we should always remember that it's His sovereign will and gracious choice that gave us that advantage. We have nothing to boast about it.
God used Assyrians as a rod to punish His people when they erred and went away from Him. Isa.10:5. However the Assyrians did not understand that it was Jehovah who was using them. They boasted upon their strength and achievements. Cf. 10:7—14. They thought their gods are powerful than the God of Israel.
God says He will punish them for their arrogant heart and haughty looks. V.12b. It is in this context the Lord asks “Shall the ax boast itself against him who chops with it?”
Arrogance of a chopper, a rod or any other tool is just foolishness indeed. It is the master's good pleasure that He chose to use it. An instrument has nothing to glory in.
If the Lord uses us for any of His purposes, remember it's His kind preference. Never boast upon our efficiency, capability or accomplishment. But be humble and submissive that He may continue to use us for His glory.