John 2.13-16: When it was almost time for the Jewish Passover, Jesus went up to Jerusalem. In the temple courts he found people selling cattle, sheep and doves, and others sitting at tables exchanging money. So he made a whip out of cords, and drove all from the temple courts, both sheep and cattle; he scattered the coins of the money changers and overturned their tables. To those who sold doves he said, “Get these out of here! Stop turning my Father’s house into a market!”
The preferred sacrifice to be offered at the temple was a lamb. But a provision is made in the Levitical code for the poor: Leviticus 5.7 Anyone who cannot afford a lamb is to bring two doves or two young pigeons to the Lord as a penalty for their sin—one for a sin offering and the other for a burnt offering. By going after the dove sellers we see Jesus directly attacking the group who were having economic dealings with the poor. When the poor would go to the temple they would head for the dove sellers. The point being, while we know that Jesus was upset about economic exploitation going on in the temple, his focus on the dove sellers sharpens the message and priorities. Jesus doesn't, for instance, go after the sellers of lambs. Jesus's anger is stirred at the way the poor are being treated and economically exploited. -Experimental Theology
DA Carson
John detects in the experiences of David a prophetic paradigm that anticipates what must take place in the life of "great David's greater Son." That explains why the words in 2:17... change the tense to the future... For John, the manner by which Jesus will be "consumed" is doubtless his death. If his disciples remembered these words at the time, they probably focused on the zeal, not on the manner of the "consumption." Only later would they detect in these words a reference to his death (cf. 2:22). (DA Carson, The Gospel According to John, p. 180)