תהילים מה:ב פירוש: רש״י

My heart is astir In this manner, the Psalmist commenced his song: My heart caused a good theme to swarm within me in your praise, O Torah scholar.

is astir Heb. רחש, an expression of moving, and so is every expression of swarming and crawling.

I say, “My works are for a king” This song, which I have founded and composed, I say to one who is fit to be a king, as it is stated (Prov. 8:15): “Kings reign with me.”