Thou lovest righteousness, and hatest wickedness: therefore God, Thy God, hath anointed Thee with the oil of gladness above Thy fellows. – Psalm 45:7

“Thou lovest righteousness, and hatest wickedness.” The perfect righteousness of Christ has brought to Him this gladness, because perfect holiness there must be before there can be perfect happiness. Sin is the enemy of joy. Let the sinner say what he likes, sin can no more dwell with real joy than the lion will lie down with the lamb. To be perfectly glad you must be perfectly cleansed from sin, for until you are so cleansed you cannot possess the oil of gladness to the measure that Christ possessed it. As the believer is delivered from the power of sin he is brought into a condition in which the joy of the Lord can more and more abide in him. Now, every way Jesus loved righteousness intensely and hated wickedness intensely. He died that He might establish righteousness and that He might destroy wickedness from off the face of the earth; therefore, it is that He has greater gladness, because He had greater holiness. Moreover, you know that in any holy enterprise if the business succeeds the joy of the worker is proportionate to the trial it has cost him. In the great battle of righteousness our Lord has led the van, in the great fight against wickedness our Savior has borne the brunt of the battle, therefore, because He to the death loved righteousness and to the agony and bloody sweat strove against sin, the accomplished conquest brings Him the greatest joy. He has done the most for the good cause, and therefore He is anointed with the oil of gladness above His fellows.

To the unrighteous the oil of gladness cannot come, but to the righteous there ariseth light even in darkness. “There is no peace saith my God, unto the wicked.” Therefore, is the Spirit of the Lord God upon Him that He may give the oil of joy to His own chosen, and make them righteous, even as He is righteous, glad as He is glad. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1273.cfm