רָ֘חַ֤שׁ לִבִּ֨י ׀ דָּ֘בָ֤ר ט֗וֹב אֹמֵ֣ר אָ֭נִי מַעֲשַׂ֣י לְמֶ֑לֶךְ לְ֝שׁוֹנִ֗י עֵ֤ט ׀ סוֹפֵ֬ר מָהִֽיר׃
עס ייִרט מײַן האַרץ מיטן שײנעם װאָרט, איך װעל פֿירזאָגן מײַנע לידער צום מלך;מײַן צונג איז די פּען פֿון אַ שרײַבער אַ פֿלינקן.
Rashi
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.
Rashi
is astir Heb. רחש, an expression of moving, and so is every expression of swarming and crawling.
Rashi
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.”
Rashi
my tongue is as poetic as the pen of an expert scribe. I saw in the commentary of Rabbi Moses the Preacher: מָהִיר in Arabic means expert.