John Chrysostom
Another evangelist relates that, when He drove them out, He said: "My house shall be called a house of prayer, but you have made it a den of thieves" (Mt 21:13). Saint John expresses it thus: "Do not make My Father's house a house of trade" (Jn 2:16).
The evangelists do not contradict one another. They show that He did this twice, and that the two events did not happen at the same time. The first time He did it at the beginning of His preaching. The second time He did it when He was already going to His Passion.
For this reason, on the last occasion He used stronger words, calling the place a den of thieves. At the beginning of the signs He did not speak so, but used a milder rebuke. Thus it is likely that He did this twice.
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He expresses His unity with the Master of the house not only by His deeds, but also by His very words. He does not say, the holy house, but, the house of My Father. See, He calls Him His Father, and they are not indignant at this. They thought He was speaking in a general way.
But later, when He expressed this more clearly and suggested His equality with the Father, they fell into rage.