Jehovah is on my side; I will not fear: What can man do unto me?
The Lord is on my side, or, he is "for me." Once his justice was against me, but now he is my reconciled God, and engaged on my behalf. The Psalmist naturally rejoiced in the divine help; all men turned against him, but God was his defender and advocate, accomplishing the divine purposes of his grace.
David reached the throne not by his own wit or men's favor, but appointed by God Himself. He had faced mortal dangers a hundred times over; God alone delivered him. This temporal kingdom figures the eternal spiritual kingdom of Christ, in whom David's person is fulfilled.
AI summary
Commenting on Psalm 118:1-29
The LORD [is] on my side; I will not fear: what can man do unto me? (c) Being exalted to this estate, he assured himself to have man ever to be his enemy. Yet he did not doubt that God would maintain him, because he had placed him.