Not long before Jesus’ entry into Jerusalem, the Pharisees had asked people to look out for Jesus so they could arrest Him. There was a suggestion that He might try to sneak into Jerusalem, or at least go unnoticed.
Not Jesus. As he entered Jerusalem on the back of a donkey, the whole city, it seemed was out to welcome him:
Matthew 21:8 Most of the crowd spread their garments on the road ahead of him, and others cut branches from the trees and spread them on the road. Jesus was in the center of the procession, and the people all around him were shouting,
They were praising Jesus as the Son of David—effectively recognising him as the Messiah.
Matthew tells us
Matthew 21:10 The entire city of Jerusalem was in an uproar as he entered.
There was no need for spies or informers: the Pharisees knew exactly where Jesus was:
Luke 19:39 But some of the Pharisees among the crowd said, ‘Teacher, rebuke your followers for saying things like that!’
But:
John 12:19 Then the Pharisees said to each other, ‘There’s nothing we can do. Look, everyone has gone after him!’
Even so, Jesus managed to slip away (John says that Jesus was hidden from the crowd) and visit the Temple briefly:
Mark 11:11 So Jesus came to Jerusalem and went into the Temple. After looking around carefully at everything, he left because it was late in the afternoon. Then he returned to Bethany with the twelve disciples.