The parable of the Dis-Graced Legalist
What Jesus unmasks here is a legalistic heart, one that has imbibed the poison of Eden. 20 Such a heart sees the Lord as a slave master and not a gracious Father, as restrictive rather than generous. Everything the Father has is available to him. But the elder son’s heart is closed, and as far as he is concerned nothing is his. He was at home, but he was in a more distant place than his younger brother. He thought he had to earn by right what he could only enjoy by grace.
Sinclair Ferguson, The Whole Christ: Legalism, Antinomianism, and Gospel Assurance—Why the Marrow Controversy Still Matters (p. 107). Crossway. Kindle Edition.