I am a companion to all those who fear thee He does not simply speak of the brotherly love and concord which true believers cultivate among themselves, but intimates that, whenever he met with any individual who feared God, he gave him his hand in token 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, 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 which prevail every where in the world. We see how worldly men array their troops against God, and assist one another in their attempts to overthrow his worship. The more then is it necessary for the children of God to be stirred up to the maintenance of 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.

I am a companion of all them that fear thee - I find my associates and friends among those who worship thee; not with the profane and the wicked. "A man is known by the company that he keeps;" and it is an evidence of piety when we seek our companions and friends among the pious. It shows where the heart is; what the preferences are; what are the tastes; what is the real condition of the soul. We seek our friends in accordance with our tastes and preferences; our love to God is indicated by our love to his friends. Compare Psalm 139:21-22.
And of them that keep thy precepts - That obey thy law. On the sentiment here, compare the notes at Psalm 1:1. A man may determine much in regard to his own character by asking himself what is the character of his chosen friends and companions. A member of a church should regard it as a dark sign against himself in regard to his piety, if his chosen friends are taken from the world, and not from the professed friends of God; if he finds more pleasure in their society, and in the scenes where they meet, than he does in the society of Christians however humble, or in places where they assemble for prayer and praise.

I am a companion - This was the natural consequence of his own conversion; he abandoned the workers of iniquity, and associated with them that feared the Lord.

I [am] a (d) companion of all [them] that fear thee, and of them that keep thy precepts.
(d) Not only in mutual consent, but also with aid and help.

I am a companion of all them that fear thee,.... Not of the rich and mighty, much less of the wicked and ungodly; but of such who had the true fear of God upon their hearts, and before their eyes; who feared the Lord and his goodness, and truly served and worshipped him; even "all" of these, whether poor or rich, of whatsoever condition, or of whatsoever nation, being no respecter of persons. With these he was a partner in the blessings of the covenant, in the promises of it, in the graces of the Spirit, and in a right and meetness for the same eternal glory and happiness: he went in company with them to the house of God, and joined with them in all acts of religious worship; he conversed privately with them about what God had done for the souls of him and them; he delighted in their company; he sympathized with them in their troubles; and was a companion with them in their tribulation, sorrows, and sufferings, as well as in their joys and comforts;
and of them that keep thy precepts; as all such do who truly fear the Lord; for by the fear of the Lord men depart from evil, and cannot do those things that others do; cannot allow themselves in a wilful transgression of the divine precepts; but, influenced by the fear of God, observe and keep them.

The communion of the saints. Delight in their company is an evidence of belonging to them (Psalm 16:3; Amos 3:3; Malachi 3:16).