Dialogue with Trypho
Chapter 107: The same is taught from the history of Jonah
"And that He would rise again on the third day after the crucifixion is written in the memoirs when some of your nation, questioning Him, said, 'Show us a sign;' and He replied to them, 'An evil and adulterous generation seeks after a sign; and no sign shall be given them, except the sign of Jonah.' Since He spoke this in a mysterious way, it was understood by the audience that after His crucifixion He would rise again on the third day.
He showed that your generation was more wicked and more adulterous than the city of Nineveh; for when Jonah preached to them, after being cast up on the third day from the belly of the great fish, and said they would all perish after three (in other versions, forty) days, they proclaimed a fast for all beings, men and beasts, with sackcloth and earnest lamentation, with true repentance from the heart, and turning away from unrighteousness, believing that God is merciful and kind to all who turn from wickedness; so that the king of that city himself, along with his nobles, put on sackcloth, remained fasting and praying, and obtained their request that the city should not be overthrown.
But when Jonah was upset that on the (fortieth) third day, as he proclaimed, the city was not overthrown, [God] used the example of a gourd that suddenly sprang from the earth, under which Jonah sat and was shaded from the heat, to teach him a lesson. The gourd had sprung up suddenly, and Jonah had neither planted nor watered it, yet it provided him shade. When it withered away, Jonah was grieved, and [God] showed him that he was unjustly displeased because Nineveh had not been overthrown. [God] said, 'You had pity on the gourd, for which you did not labor or make it grow; it came up in a night and perished in a night.
And should I not spare Nineveh, the great city, where more than 120,000 people live who cannot discern between their right hand and their left hand, and also much cattle?'"