Psalm 19:8 (ESV)

8 the precepts of the LORD are right, rejoicing the heart; the commandment of the LORD is pure, enlightening the eyes;

The precepts of the Lord are right. They bring people on the right path where they do not stumble. And therefore, they lead us to the right destination. That gives joy. Psalm 119:14 connects with this text: In the way of your testimonies I delight as much as in all riches (see also Psalm 1:2 which reads his delight is in the law of the Lord).

At its deepest level, the Christian life may be typified as a joyful journey, even when circumstances are sometimes troublesome. The command of the Lord gives a clear view of what is good and what is bad. It is like a lamp shining on the path that you must take. For the commandment is a lamp and the teaching a light it says in Proverbs 6:23a, and in Luke 8:16 we read …that those who enter may see the light.