NOTES for Jer 32:1-25
The purchase of a field during the siege of the city is a distinctive prophetic action, the Lord's promise of salvation expressed through gestures. From the point of view of common sense, such a transaction is completely meaningless, especially since the prophet knows that the whole people must go into Babylonian captivity. But that makes his action all the more expressive.
In sacred history the Lord often gives promises that, at first glance, look like madness. For example: the promise of a son to the hundred-year-old Abraham, or the promise of victory to the young Gideon with a small army. Now, on the eve of a national catastrophe, the Lord promises Israel prosperity and peace. The prophets teach us to live in expectation of the fulfillment of God's promises and, in situations of defeat and decline, to see hope.