This is Psalm 119 for the Sixth Sunday in Ordinary Time for Year A as set by Paul Mason from Psalms for All Time Vol 3.
I suppose it is a sung Old Testament Beatitude.
Response
Blessed, blessed are they who follow the law of the Lord.
1 Blessed are those whose way is blameless,
Who walk in the law of the Lord.
Blessed are those who keep his decrees!
With all their hearts they seek him.
2 You have laid down your precepts to be carefully kept.
May my ways be firm in keeping your statutes.
3 Deal bountifully with your servant,
That I may live and keep your word.
Open my eyes that I may see the wonders of your law.
4 Lord, teach me the way of your statutes,
And I will keep them to the end.
Grant me insight that I may keep your law,
And observe it whole-heartedly.