He had recently rebuked them after healing a woman who was bent over for 18 years from a spirit of infirmity on the Sabbath in the synagogues. Jesus declared the sick being healed by God on the Sabbath in the synagogue would glorify God making their Sabbath rule asinine.
The Pharisees were silent because because they fear Him and His wisdom. Many people were happy after He set them free from the heavy Sabbath rules. The people could be healed on the Sabbath in the Synagogue because it would glorify God. The establishment was afraid they would be the point of anger from the people after Jesus set them free from the spirit of Sabbath bondage. Silently in their hearts the rule makers and enforcers wanted Jesus to perform this healing on the Sabbath in order to trap Him so that they would have a reason to destroy Him.
Again, by the Spirit of the Lord and the Wisdom of God, Jesus makes the point of the foolishness of the difficult heavy rules the establishment placed on people. He points out that these political hypocrites violate their own rules by doing good deeds on the Sabbath if they benefit from it or the things they own would benifit. They could not argue with Jesus because they could not even keep their own Sabbath laws.