The First Sign: Abstention From Marriage And Childbearing (Jeremiah 16:2-4).
Jeremiah's abstention from marriage and childbearing was in order to underline the awful future that waited those who were married, along with their wives, sons and daughters.
“You shall not take for yourself a wife,
Nor shall you have sons or daughters, in this place.
For thus says YHWH concerning the sons,
And concerning the daughters who are born in this place,
And concerning their mothers who bore them,
And concerning their fathers who begat them in this land,”
They will die grievous deaths (deaths from diseases),
They will not be lamented, nor will they be buried.
They will be as dung on the face of the ground,
And they will be consumed by the sword, and by famine,
And their dead bodies will be food for the birds of the heavens,
And for the beasts of the earth.”
The first sign that was to be given by Jeremiah was that of abstention from marrying and having children. To us that might not be seen as so unusual, but it was very different for men in Israel in those days. For every Israelite adult male saw marriage and bearing children as being his most important basic duty and as being the most necessary requirement of life. By it he was seen as not only fulfilling his own destiny (‘be fruitful and multiply' - Genesis 1:28), but as also perpetuating his name, and ensuring the passing on of his inheritance through the family. Marriage was considered to form the very basis of society. And it was not only for his own sake. It was in order that he and his successors might provide security for the whole family. It was seen as the very foundation of family life, providing stability for all, and ensuring its continual growth and prosperity. Not to marry was greatly frowned on, and almost unknown, and not to have children was seen as an especially great grief, and a catastrophe for the family, which was one reason why dual marriage was allowed
So when Jeremiah was told by God not to take a wife for himself and have sons and daughters, he was being asked to go against the very tenets of society, to forego a basic right, and to be willing to face up to the opprobrium that would almost certainly follow. But the reason for the abstention was clearly laid out. It was in order to get over the fact that, in view of Judah's future prospects, not being married and not having sons and daughters would be seen as a great advantage, because death would be so rampant. Fathers, mothers, sons and daughters would all die grievous deaths through diseases, and they would die in such circumstances that they would not be lamented because those deaths would be so much a part of what was happening around them that there would be no opportunity for mourning, and no one to do the mourning. Their dead bodies would lie unburied, lying scattered like manure on the fields, and sword and famine would continue to contribute to their numbers with the result that they would become the prey of scavenger birds (vultures, etc.) and the dinner of equally unpleasant scavengers in the animal world. And that was only something which could happen because death had claimed the whole family so that none was left to fulfil the crucial burial duties (compare Jeremiah 9:22 and see the piteous example in 2 Samuel 21:10). To be left unburied and to be eaten by scavengers was seen by Israelites as the most terrible of deaths.
The intention behind his abstinence from marriage was in order to cause people to ask him why he was not married, at which point he would explain the reasons so as to bring home YHWH's warnings.