Adam Clarke on Matthew 16:4

Wicked and adulterous generation - The Jewish people are represented in the Sacred Writings as married to the Most High; but, like a disloyal wife, forsaking their true husband, and uniting themselves to Satan and sin. Seeketh after a sign, σημειον επιζητει, seeketh sign upon sign, or, still another sign. Our blessed Lord had already wrought miracles sufficient to demonstrate both his Divine mission and his divinity; only one was farther necessary to take away the scandal of his cross and death, to fulfill the Scriptures, and to establish the Christian religion; and that was, his resurrection from the dead, which, he here states, was typified in the case of Jonah.