David
Psalm 40:9ESV·traditional attribution

I have told the glad news of deliverance in the great congregation; behold, I have not restrained my lips, as you know, O LORD.

John Calvin Reformed @genevareformer

PSALM 40 David, being delivered from some great danger, and it may be, not from one only, but from many, extols very highly the grace of God, and by means of this, his soul is filled with admiration of the providence of God, which extends itself to the whole human race.

Commenting on Psalm 40:1-17

C.H. Spurgeon Reformed Baptist @princeofpreachers

I have preached righteousness in the great congregation. The purest morality and the highest holiness were preached by Jesus. Righteousness divine was his theme. Our Lord's whole life was a sermon, eloquent beyond compare, and it is heard each day by myriads. Moreover, he never shunned in his ministry to declare the whole counsel of God; God's great plan of righteousness he plainly set forth.

Matthew Henry Presbyterian @wholebiblehenry

The psalmist, being struck with amazement at the wonderful works that God had done for his people, is strangely carried out here to foretel that work of wonder which excels all the rest and is the foundation and fountain of all, that of our redemption by our Lord Jesus Christ.

Commenting on Psalm 40:6-10