All the paths of the Lord - All the ways that the Lord takes; all that He commands; all that He does. The “paths of the Lord” denote the course in which He himself walks, or His dealings with His creatures. In the previous verse, the psalmist had said that the Lord would teach “His way” to the “meek;” he now says that all His ways are ways of mercy and of truth; or that all will be found to be in the direction of mercy and of truth.
Are mercy and truth - In all His dealings with those who “keep his covenant” He shows Himself to be at the same time merciful and true: compassionate toward their errors; faithful to His own promises.
To such as keep his covenant - To those who are His friends; to those who are faithful to Him. This expression is often used to denote those who are the true people of God, Genesis 17:9-10; Exodus 19:5; Deuteronomy 29:9; Psalms 132:12. The word “covenant” here is equivalent to “command or law;” and the idea is, that if they keep His laws they will find Him to be merciful and true. On the meaning of the word “covenant,” see Acts 7:8, note; Hebrews 8:8, note; Hebrews 9:16-17, note.
And his testimonies - The word “testimony” in the Scripture, in this connection, refers to that to which God bears witness as “true;” or that which He has declared to be truth. In this sense, the phrase here means those who maintain His truth; or who abide by what He has pronounced to be true. The word is very often used in the Scriptures to denote the truth of God and the commandments of God. In all such cases, there is the underlying idea that the command or the statement referred to is that to which God bears witness as true or right.