John Gill Commentary Matthew 16:4

"An evil and adulterous generation seeketh after a sign; and there shall no sign be given unto it, but the sign of Jonah. And he left them, and departed." — Matthew 16:4 (ASV)

A wicked and adulterous generation
He says the same things here, as he did to the Pharisees on a like occasion, in (Matthew 12:39) (See Gill on Matthew 12:39).

And he left them ;
as persons hardened, perverse, and incurable, and as unworthy to be conversed with:

and departed :
to the ship which brought him thither, and went in it to the other side of the sea of Galilee; see (Mark 8:13) .