I was talking to someone recently about musical instruments being used in singing about God, and he agreed that psalms seemed to include musical instruments as being permissible, but he added the caveat, "Do you really want to take your chances with God? He said sing, He may not have meant singing with instruments."
We should not think that God is trying to catch folks on some "Simon Didn't Say" technicality. "Therefore, since we have a great high priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession....let us draw near with confidence to the throne of grace, so that we may receive mercy and find grace to help in time of need." (Heb 4:14-16)
We can have confidence and draw near the throne, because our God is a God or mercy and grace.