Matthew 21:22

“And all things, whatever you shall ask in prayer, believing, you shall receive.”

Jesus then caps off His words by underlining the importance of taking God at His word. His point is that when they are praying for something, praying through to a position of faith will result in their receiving it. Note the connection with prayer. The idea is not of some outlandish ‘faith' used outside the purposes of God in order to obtain anything that we want, but on the importance of faith in seeking the will of God. Full confidence in God and true prayer is required if they are to accomplish His will, and achieve great spiritual things. For then the glory will go to God.

This emphasis on prayer reminds us that that was precisely where Jesus had seen unbelieving Israel as lacking in Matthew 21:13. Had their thoughts been more on true prayer, and less on making money, they would not have needed Him to do what He did, and their way would have prospered. But for many prayer had become just a formality (compare Matthew 6:5; Luke 18:11). Thus they were already partly withered.