These words are repeated four times in this verse, to show how vehemently desirous the psalmist was that God might have his due praise and glory; and of how great necessity and importance it was to men to perform this great, though much neglected, duty. Unto our King; for so he is in a special manner.
Related Commentaries of Psalms 47:6
Psalms 47:6
6 Sing praises to God, sing praises: sing praises unto our King, sing praises.