King James Version (KJV)
Then on that day David delivered first this psalm of thanks unto the LORD, by the hand of Asaph and his brethren.
Modern English
Then on that day David first appointed that thanksgiving be sung to the LORD by Asaph and his brothers.
Hebrew
בַּיּ֣וֹם הַה֗וּא אָ֣ז נָתַ֣ן דָּוִיד֮ בָּרֹ֣אשׁ לְהֹד֣וֹת לַ֣יהוָה בְּיַ֣ד אָסָ֥ף וְאֶחָֽיו׃
bayvom hahvʾ ʾaz natan daviyd baroʾsh lhodvot layhvah byad ʾasaf vʾeḥayv