Sometimes we tend to forget some of the other aspects of the parable of the Prodigal Son.
The older brother figures in the picture as well-—it seems that his fidelity to his father was not entirely based on love, and because of that, he could not experience a quality of joy at the return of his brother.
We often ask ourselves how we fit the portrait of the prodigal—is it worthwhile sometimes to consider how we may fit the portrait of the older brother? And notice that the father shows his love for both.
Another thing—the prodigal son, being the younger son, by the Hebraic code of family life, was not even entitled to ask for his inheritance. This was to be handed over to the older brother at the proper time, who would then dispense it according to his good will.
That the younger son asked for his inheritance was a disrespectful request according to that culture. The fact that this must have rankled the older brother is another way in which we can search our hearts to see if, by chance, we could have that kind of carnal and fraternal jealousy in our own hearts.
Again—the Father loved them both.
The “Our Father” of “La Civiltà Cattolica” - (comparison to Muslim version)
HOLDING HANDS AT THE OUR FATHER?
Our Father - In Heaven (Dr. Scott Hahn)
I think the other son shows that sometimes our "righteousness" can be sin :)
I think it also reveals the spirit of envy, which causes us to compare ourselves with others.