Amen! It occurred to me this morning that, in those two passages (repeated below) God takes credit for being the author and preserver of His own words. And HE also takes credit for their publication, distribution, receipt and effectiveness:
The words of the LORD [are] pure words: [as] silver tried in a furnace of earth, purified seven times. Thou shalt keep them, O LORD, thou shalt preserve them from this generation for ever. – Psalms 12:6-7 So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper [in the thing] whereto I sent it. - Isaiah 55:11
So what could man take credit for doing? He is merely the instrument of God's will in this matter, no more important than a court reporter or typesetter at Random House or camera man at Fox News - moreover, he is easily replaced by the One who created him:
And think not to say within yourselves, We have Abraham to [our] father: for I say unto you, that God is able of these stones to raise up children unto Abraham. - Matt 3:9
Indeed, if a scribe or minister has a pressing need to authenticate himself, he should say no more than this:
Do we begin again to commend ourselves? or need we, as some [others], epistles of commendation to you, or [letters] of commendation from you? Ye are our epistle written in our hearts, known and read of all men: [Forasmuch as ye are] manifestly declared to be the epistle of Christ ministered by us, written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart. - 2 Cor 3:1-3
To God be the glory, not man, never man.