Mark 3:2

They watched (parethroun). Imperfect tense, were watching on the side (or sly). Luke uses the middle voice, parethrounto, to accent their personal interest in the proceedings. It was the sabbath day and in the synagogue and they were there ready to catch him in the act if he should dare to violate their rules as he had done in the wheat fields on the previous sabbath. Probably the same Pharisees are present now as then. That they might accuse him (ina kathgorhswsin autou). So Matthew 12:10 . Luke has it "that they might find how to accuse him" (ina eurwsin kathgorein autou). They were determined to accuse him. The sabbath controversy offered the best opening. So here they are ready for business.