John 2:17

‘His disciples remembered that it was written, ‘Zeal for your House will eat into me'.'

The words cited here by John come from Psalms 69:9 and there it is also in a context where insults are being offered to God, just as they were here. We are not told when the disciples remembered the words, probably it was at the time, but it confirms to them and the readers that here is One Who fulfils the Scriptures and takes worship seriously, and is willing to be unpopular in order to purify it.

John possibly also sees in the incident a picture of rejection of the sacrificial system which Jesus has come to replace, but that is not apparent from Jesus' words, although hinted at in what follows. But certainly it was a sign that the old waters of Judaism needed transforming and changing into something better.