Jesus is sighting deeply in His spirit.

Jesus is sighting deeply in His spirit (Mk. 8:12). 

The reason is because an evil and adulterous generation seeks after a sign (Mt. 16:4)

and we, like the Pharisees, seek from Him a sign from heaven (Mk. 8:11).

Maybe the reason Jesus is sighting deeply in His spirit is

because we aren’t satisfied with Jesus’ death on the cross and rose again after three days (Cf. v. 31)

which the sign of the prophet Jonah points to (Mt. 12:39) and still seek after the sign?