After he had spoken, a Pharisee invited him to dine at his home. He entered and reclined at table to eat. The Pharisee was amazed to see that he did not observe the prescribed washing before the meal. The Lord said to him, "Oh you Pharisees! Although you cleanse the outside of the cup and the dish, inside you are filled with plunder and evil. You fools! Did not the maker of the outside also make the inside? But as to what is within, give alms, and behold, everything will be clean for you. (Lk 11:37-41)
Pharisee invited him to dine at his house. Jesus accepted the invitation and went in to recline at table with him. Jesus was not against Pharisees in general. There were also Pharisees who lived their lives more in line with that of Jesus and his teachings. Jesus associated with them and communed with them. Jesus accepted table fellowship with Pharisees.
Being a Pharisee he expected Jesus to behave like him and observe every rule of purification. Prescribed rules of purification were to make a Jew ever ready and ever be available for divine intervention. Every meal at home was also like the Passover meal and every entry into the home was equal to entry into to the temple. In short the rules of purification made him sacred.
Jesus did not deny the external rules. External rules were good and they were needed. Internal purification was as important as the external ones. Rules of purification of external as well as internal make the one complete (integral) that fulfils them. Jesus did not deny the external rules but for the internal he spoke about alms giving. Alms giving (though an external pious practice) becomes an internal one because of its concern for the other.
