John Gill Commentary Psalms 57:9

"I will give thanks unto thee, O Lord, among the peoples: I will sing praises unto thee among the nations." — Psalms 57:9 (ASV)

I will praise thee, O Lord, among the people
Either among the people of Israel, as Aben Ezra, when each of the tribes meet together; and so it denotes the public manner in which he would praise God for his salvation: or among the Gentiles, as the following clause shows;

I will sing unto thee among the nations :
the Apostle Paul seems to have reference to this passage in (Romans 15:9) ; which he produces as a proof of the Gentiles glorifying God for his mercy in sending the Gospel among them, and calling them by his grace; by which they appeared to be his chosen and redeemed ones; and in forming them into Gospel churches, among whom his praise was sung: for this supposes something to be done among the Gentiles, which should occasion praise; and here the psalmist represents the Messiah, who in his ministers and members praise God for his wonderful mercy to the Gentile world, as follows.