Matthew's account of this incident is fuller than Mark's. Probably Mark just summarized it here to parallel 7:1-23 and so advance his theme of discipleship training.
8:11 Matthew noted that the Sadducees accompanied the Pharisees (Matt. 15:1). They came out from Jerusalem again to argue, not to learn. They asked Jesus to provide some celestial confirmation of His divine authority. They had previously concluded that His power came from Satan (3:22). The miracles that Jesus performed did not convince them. They were not requesting another one of these but a different type of verification perhaps similar to those God gave the Israelites at Mt. Sinai to authenticate Moses as His servant. They did this to subject Jesus to a trial (Gr. peirazo) that would reveal His true character. They hoped to expose Him as a phony.
". . . the Sadducees were a wealthy, conservative party concentrated in Jerusalem. Their members were from aristocratic families of patrician and priestly stock. They refused adherence to the tradition of the elders and advocated a rigorous application of the law of Moses to the life of the nation. In general, they espoused a political and religious policy, including cooperation with Rome, aimed at preserving the status quo."191
8:12 The Greek word translated "sighing deeply"is anastenazo.
"It describes Jesus' grief and disappointment when faced with the unbelief of those who, because of their spiritual privileges, ought to have been more responsive to him."192
The spirit was Jesus' human spirit. The contemporary Jews who opposed Jesus constituted the generation to which He referred. He refused to give the type of sign they requested because the evidence that He had presented was more than adequate to convince an open-minded person. Jesus distinguished between miracles (Gr. dynamis) and signs (Gr. semeion) by using the second word here. He had given plenty of miracles to bolster faith. He would not give a sign to those bent on disbelieving. From this Mark's readers were to learn that Jesus' miracles were ample proof of His deity.
8:13 Jesus again left unbelievers (cf. 4:35; 7:24). He departed for the northeast coast of the lake.
This incident was and is a lesson to disciples on the importance of accepting the evidence that Jesus has given concerning His supernatural person.
