2 Corinthians 3:5

Not that we are sufficient of ourselves
Though we are sufficient for this work to which God has called us, and have such trust and confidence that he has blessed and owned us, and done such great things by us; yet we do not ascribe anything to ourselves, to any power of ours, to any self-sufficiency in us: for "we are not sufficient of ourselves" neither for the work of the ministry, nor for the conversion of sinners, nor for faith and hope in God, nor for any spiritual work whatever; not even to think anything as of ourselves; any good thing, either for our own use and benefit, or for the advantage of others; we are not able of ourselves to meditate with judgment and affection upon the word of God, to study the Scriptures, to collect from them things fit for the ministry; and much less with freedom and boldness to speak of them to edification; and still less able to impress them upon the heart: for though you who are the epistle of Christ are ministered by us, yet not by any power and self-sufficiency of ours;

but our sufficiency is of God;
to think, to speak, and to act for his glory.