But he [the older brother] was angry and refused to go in. His father came out and entreated him, but he answered his father, 'Look, these many years I have served you, and I never disobeyed your command, yet you never gave me a young goat, that I might celebrate with my friends. But when this son of yours came, who has devoured your property with prostitutes, you killed the fattened calf for him!' And he said to him, 'Son, you are always with me, and all that is mine is yours. It was fitting to celebrate and be glad, for this your brother was dead, and is alive; he was lost, and is found.'" (Luke 15:28-32 ESV)
Tim Keller has rightly noted that there are two lost sons in this parable, and the saddest sight is the outwardly-obedient older brother who cannot stand to see his younger brother received again by his father, presumably because he feels his inheritance may be at stake. He is resentful for any expenditure that he himself does not receive.
Neither son seems to love, or have loved, his father simply for the love that the father bestows. One wants his money so he can run, and the other stays so he can get his portion on site.
"Here, then, is Jesus’ radical redefinition of what is wrong with us. Nearly everyone defines sin as breaking a list of rules. Jesus, though, shows us that a man who has violated virtually nothing on the list of moral misbehaviors can be every bit as spiritually lost as the most profligate, immoral person. Why? Because sin is not just breaking the rules, it is putting yourself in the place of God as Savior, Lord, and Judge just as each son sought to displace the authority of the father in his own life.” (Tim Keller, The Prodigal God)
Painting above is The Return of the Prodigal Son by Rembrandt, 1669.