en_tn_condensed/psa/042/008.md

Yahweh will command his covenant faithfulness in the daytime

The writer speaks of Yahweh's covenant faithfulness as if it were a person whom he commands to be with him. The abstract noun "faithfulness" can be translated as an adjective. Alternate translation: "Yahweh will show me his covenant faithfulness in the daytime" or "Yahweh will show me in the daytime how faithful he is to his covenant" (See: rc://en/ta/man/jit/figs-metaphor)

his song

Possible meanings are 1) "the song that he gives me" or "the song about him"

the God of my life

"the God who gives me life"