Adam Clarke on Matthew 21:15

The chief priests - were sore displeased - Or, were incensed. Incensed at what! At the purification of the profaned temple! This was a work they should have done themselves, but for which they had neither grace nor influence; and their pride and jealousy will not suffer them to permit others to do it. Strange as it may appear, the priesthood itself, in all corrupt times, has been ever the most forward to prevent a reform in the Church. Was it because they were conscious that a reformer would find them no better than money-changers in, and profaners of, the house of God, and that they and their system must be overturned, if the true worship of God were restored! Let him who is concerned answer this to his conscience.