Mark 8:11

And the Pharisees came forth

(κα εξηλθον ο Φαρισαιο). At once they met Jesus and opened a controversy. Matthew 16:1 adds "and Sadducees," the first time these two parties appear together against Jesus. See discussion on Matthew 16:1. The Pharisees and Herodians had already joined hands against Jesus in the sabbath controversy (Mark 3:6). Theybegan to question with him

(ηρξαντο συνζητειν αυτω). Dispute, not mere inquiry, associative instrumental case of αυτο. They began at once and kept it up (present infinitive).