John Gill Commentary Psalms 119:151

"Thou art nigh, O Jehovah; And all thy commandments are truth." — Psalms 119:151 (ASV)

You [are] near, O Lord
This was the comfort of the psalmist, that though his enemies drew nigh with a mischievous design upon him, yet his God was also near, and nearer than they; he was near as to relation to him, being his God and Father; near as to union, the bond of which is his everlasting love, which can never be dissolved; near as to communion, which he admits all your people to at one time or another; so that they are said to be "a people near unto the Lord"; (Psalms 148:14) ; and near as to his gracious presence, and the divine assistance he affords; he is a present help in time of need; he is nigh to all that call on him in truth, and in all things in which they do call upon him for, (Psalms 145:18) (Deuteronomy 4:7) ;

and all your commandments [are] truth ;
not only the precepts of the word of God, but his covenant, and the promises of it; the word which he has commanded to a thousand generations, (Psalms 105:8) ; and even the whole word of God, doctrines and duties; see (John 17:17) .