There is great significance in that ‘believed God’ (ver. 5).  The foundation of all true repentance is crediting God’s word of threatening, and therefore realising the danger, as well as the disobedience, of our sin.  We shall be wise if we pass by the human instrument, and hear God speaking through the Prophet.  Never mind about Jonah, believe God.

We learn from the Ninevites what is true repentance They brought no sacrifices or offerings, but sorrow, self-abasement, and amendment.  The characteristic sin of a great military power would be ‘violence,’ and that is the specific evil from which they vow to turn.  The loftiest lesson which prophets found Israel so slow to learn, ’A broken and a contrite heart Thou wilt not despise,’ was learned by these heathens.  We need it no less.  Nineveh repented on a peradventure that their repentance might avail.  How pathetic that ‘Who can tell?’ (ver. 9) is!  We know what they hoped.  Their doubt might give fervour to their cries, but our certainty should give deeper earnestness and confidence to ours.

The deepest meaning of the whole narrative is set forth in our Lord’s use of it, when He holds up the men of Nineveh as a condemnatory instance to the hardened consciences of His hearers.  Probably the very purpose of the book was to show Israel that the despised and yet dreaded heathen were more susceptible to the voice of God than they were:  ’I will provoke you to jealousy by them which are no people.’  The story was a smiting blow to the proud exclusiveness and self-complacent contempt of prophetic warnings, which marked the entire history of God’s people.  As Ezekiel was told:  ’Thou are not sent ... to many peoples of a strange speech and of an hard language....  Surely, if I sent thee to them, they would hearken unto thee.  But the house of Israel will not hearken unto thee.’  It is ever true that long familiarity with the solemn thoughts of God’s judgment and punishment of sin abates their impression on us.  Our Puritan forefathers used to talk about ‘gospel-hardened sinners,’ and there are many such among us.  The man who lives by Niagara does not hear its roar as a stranger does.  The men of Nineveh will rise in the judgment with other generations than that which was ‘this generation’ in Christ’s time; and that which is ‘this generation’ to-day will, in many of its members, be condemned by them.

But the wave of feeling soon retired, and there is no reason to believe that more than a transient impression was made.  It does not seem certain that the Ninevites knew what ‘God’ they hoped to appease.  Probably their pantheon was undisturbed, and their repentance lasted no longer than their fear.  Transient repentance leaves the heart harder than before, as half-melted ice freezes again more dense.  Let us beware of frost on the back of a thaw.  ‘Repentance which is repented of’ is worse than none.