At last Rachel has a child of her own, Joseph, meaning ‘he will add’. She had been blessed with her own child late in the day, only after having resorted to unlawful means to obtain a son through Bilhah.
Some do something similar to Rachel with their own assurance. Some constantly attribute this and that event in their lives to the Lord, as if they were full of the joy of faith, but it is not real. If the day comes when they are really given assurance, they will know they have been fabricating something which is not real. We should never speak in swelling terms when we do not really feel it. Pray for real blessing from the Lord, and do not try to manufacture your own. It is impossible for us to deceive ourselves about these things.
Why did God allow it? Well in the goodness of God, he allowed that terrible mistake to be made for the benefit of subsequent generations. God does not just say to mankind, marriage is between one man and one woman for life; God does not just arbitrarily command it. He says, ‘Look what happens when you try it another way. Look at this family with a godly father’, and yet he cannot hold the family together in happiness and bliss, because of this departure from the God given pattern. God in his goodness not only gives the command, but gives the explanation for the command also in an event like this. So actually, miserable as it was for them, it is the will of God that we should look into this account and see the lesson. The same is true with other polygamous relations in the Old Testament. They are holding up a lens to show us. There is God, who is not obliged to do this, in his great kindness, giving us the reasons for his commands, and explaining it so carefully through these examples of when things go wrong.