John Gill Commentary Psalms 47:6

"Sing praise to God, sing praises: Sing praises unto our King, sing praises." — Psalms 47:6 (ASV)

Sing praises to God
That is gone up with a shout, Christ Jesus, our ascended Lord and King, as the apostles did at the time of his ascension, (Luke 24:52Luke 24:53);

sing praises; sing praises to our King, sing praises :
who was then made Lord and Christ, declared King of saints, and crowned with glory and honour;

The repetition of the phrase sing praises denotes frequency, constancy, fervency, and great devotion in the performance of this service; and that the ascension of Christ, the occasion of it, is of the greatest moment and importance, and requires it to be performed in such a manner.