Why did the religious leaders not want to arrest Jesus on the feast day?
The chief priests, scribes, and elders feared that arresting Jesus during the feast would cause an uproar among the people. They consulted to take Him by subtlety and kill Him, but agreed not on the feast day. The feast was the Passover week, including the whole week of unleavened bread.
Les explains that this passage in Matthew 26 comes as Jesus is finishing His sayings about prophecy and the coming kingdom. The chief priests, scribes, and elders gathered under Caiaphas and plotted to seize Jesus secretly and kill Him. But they decided against doing it on the feast day because they feared an uproar among the people. Les notes the feast was not just one day but the whole week of unleavened bread.
But they said, Not on the feast day, lest there be an uproar among the people.