David
Psalm 136:12ESV·traditional attribution

with a strong hand and an outstretched arm, for his steadfast love endures forever;

John Calvin Reformed @genevareformer

PSALM 136 The Psalmist reminds the Lord’s people, that unless they were assiduous in his praises, they were chargeable with defrauding him of what was justly due to him for his benefits. And, in mentioning each benefit, he takes particular notice of the mercy of God, to teach us how necessary it is to the proper celebration of his praises that we own everything which...

Commenting on Psalm 136:1-26

C.H. Spurgeon Reformed Baptist @princeofpreachers

With a strong hand, and with a stretched out arm. Not only the matter but the manner of the Lord's mighty acts should be the cause of our praise. We ought to bless the Lord for adverbs as well as adjectives. In the Exodus the great power and glory of Jehovah were seen. He dashed in pieces the enemy with his right hand.

Matthew Henry Presbyterian @wholebiblehenry

The great things God for Israel, when he first formed them into a people, and set up his kingdom among them, are here mentioned, as often elsewhere in the psalms, as instances both of the power of God and of the particular kindness he had for Israel. See Psa 135:8, etc. 1. He brought them out of Egypt, Psa 136:10-12.

Commenting on Psalm 136:10-22