John Gill Commentary Psalms 119:51

"The proud have had me greatly in derision: [Yet] have I not swerved from thy law." — Psalms 119:51 (ASV)

The proud have had me greatly in derision Profane sinners, proud and haughty scorners, that make a jest of religion, and scoff at everything serious and good: these derided the psalmist for his piety and religion, his principles and practices; in which he was a type of Christ, who was both the song of the drunkards, and was derided by the proud and haughty Scribes and Pharisees; as all self-righteous persons are, they who trust in themselves, and despise others, (Psalms 69:11Psalms 69:12) (Luke 16:14) (18:9) .

[yet] have I not declined from your law from walking according to it, as a rule of life and conversation; from professing and maintaining the doctrine of the word, the truths of the Gospel, he had knowledge and experience of; and from going on in the ways of God and true religion he was directed in; and this testimony the Lord himself gave of him, (1 Kings 14:8) (15:5) see (Psalms 44:19) .