Thanks for your question.  I have no idea why anyone would think that either Nahum or Zephaniah would have needed to report on any “period of divine favor” for Ninevah or for Assyria.   We know that Jonah preached in Nineveh, and that God promised to relent from sending calamity on Assyria at that time. Biblical scholars estimate that Jonah served as a prophet in either the late 9th century BC or the early eighth century BC.  To be specific, Nahum prophesied concerning Nineveh in the late seventh century BC, making the question about why he did not comment on a period of “divine favor” for Nineveh more than 150 years years earlier a seriously misinformed question!  The same for Zephaniah.

As a general rule history reports what happens, and not what does NOT happen.  It is therefore not surprising that we do not have a strong record of what did NOT happen to Assyria in the late ninth or early eighth century BC, immediately after Jonah preached to Nineveh.  Besides, Jonah did not prophesy a period of great blessing, but simply that God would relent from sending calamity on Assyria.

The implication of your question, which is clearly coming from a Muslim source, is that Muhammad somehow got this one right, when the biblical writers did not.  There are at least two reasons that this point is fantastically weak.  First of all, there is the point that the biblical writers in question lived well over one hundred years after Jonah (combined with the fact that lack of evidence is not evidence of lack).  The Bible does not get it wrong.

The second reason we can discount the statement in the Qur’an is that Muhammad said many things in his many surahs, and you can think what you want of them, but the evidence for Muhammad being a false prophet is VERY strong, including his violence, his deceits, his having sexual relations with many wives, including very young women, his decision to execute hundreds of Jews in Medina, his lack of having worked any miracles or fulfilling any bona fide biblical prophecies.  So, you should feel free to take this seemingly random statement by Muhammad for what it is worth, but this is not a biblical statement.

Here is what I think happened here.  Muhammad had almost no exposure to the New Testament, but he clearly had a fairly broad exposure to the Hebrew Bible.  I assume that he was aware of the Book of Jonah, and simply assumed that what the Book of Jonah reports is true, and that, therefore, there ensued a period of peace for Nineveh.  Muhammad simply proposed, logically, that this is what happened.  He did not learn this from any historical source, and he clearly did not receive this report by inspiration, given that he was no prophet!

John Oakes