The answer is: 40 days

Jonah 3:4 - This number is often associated with humiliation... 40 days fasting, 40 years in the wilderness.

In the Book of Jonah, the looming message of destruction hangs over Nineveh for 40 days. This timing is no coincidence; the number 40 plays a significant role throughout the Scriptures, usually linked with periods of testing and transformation. Think about the Israelites’ 40 years in the wilderness or Jesus’ 40 days fasting in the desert. Each instance represents an intermediary state — a transition between something past and something yet to come.

Interestingly, 40 appears as a theme of eventual hope too. In Jonah’s case, Nineveh is given a chance for repentance, showcasing how redemption can arise from the cliffs of impending doom. The timing is both dire and transformational, urging the city to change its ways. Did you know that Nineveh was not just any backdrop but symbolized everything that went against Israel's values during Jonah's time? It's like the superhero facing a villain who somehow might still redeem themselves.

Moreover, while many think of the austerity of fasting or wilderness wandering associated with 40, Jonah’s message gives a splash of unexpected grace—the very people the Israelites loathed were invited to face the change. This popular narrative paints a vivid picture of potential reformation, not just for Nineveh, but for anyone who bears hard truths from their own dealings. It’s much like a wakeup call with an opportunity — an invitation to transform before it’s too late. Isn't that a thought to reflect upon?