John Calvin Commentary Psalms 119:63

"I am a companion of all them that fear thee, And of them that observe thy precepts." — Psalms 119:63 (ASV)

I am a companion to all those who fear thee. He does not simply speak of the brotherly love and concord that true believers cultivate among themselves, but intimates that, whenever he met with any individual who feared God, he gave him his hand as a sign of fellowship, and that he was not only one of the number of God’s servants, but also their helper.

Such concord is undoubtedly required in all the godly, so that they may contribute to each other’s advancement in the fear of God. There seems to be a tacit comparison between this holy combination, by which the faithful mutually keep up and foster among themselves the worship of God and true godliness, and the impious associations that prevail everywhere in the world. We see how worldly men array their troops against God, and assist one another in their attempts to overthrow his worship. Therefore, it is all the more necessary for the children of God to be stirred up to maintain a holy unity.

The Psalmist commends the faithful, first, for their fearing God, and, secondly, for their observing the law. The fear of God is the root or origin of all righteousness, and by dedicating our life to His service, we manifest that His fear dwells in our hearts.