The Sefer HaMa'asiyot — the Book of Exempla — compiled by Moses Gaster in 1924 from medieval Jewish manuscripts, preserves a short and sharp story about the daughter of a Roman emperor and the sage Rabbi Yehoshua ben Chananyah.
The girl was clever and liked to sting. One day she came to the rabbi with a taunt. "Your God, you say, is a builder — the One who framed heaven and earth. Very well. Let Him build me a tent here, now, in my father's palace. Let Him perform something I can see."
Rabbi Yehoshua said nothing. But before long the princess fell ill with a skin disease severe enough that the Roman physicians ordered her isolated — placed, as was the custom, in a private tent outside the palace walls to prevent contagion. The tent she had mocked became the tent she was forced to inhabit.
When she realized what had happened, she sent word to the rabbi asking him to pray for her healing — to undo the sign.
His answer came back short. "Our God gives, but He does not take back again."
The line has more than one meaning. A sign, once granted, is not retracted; a tent pitched by Providence is not dismantled on demand. And there is a gentler reading too — the Holy One's gifts, including the gift of affliction that turns a scoffer toward prayer, are not repented of. Sometimes the answer to "show me a miracle" is a miracle we would not have asked for.