Charles Ellicott Commentary Psalms 135:3

"Praise ye Jehovah; for Jehovah is good: Sing praises unto his name; for it is pleasant." — Psalms 135:3 (ASV)

Sing praises. — Rather, play.

For it is pleasant— i.e., in this way to sing hallelujah. (Proverbs 22:18.) Others take name as the subject, and the Prayer-Book version suggested to Crashaw the beautiful hymn beginning "Come lovely name," and so on.