Once have I sworn, &c.— One thing I swear by my holiness; (I will not lie unto David:) Psalms 89:36. His seed shall endure for ever, &c. Psalms 89:37. As the moon, it shall be fixed firm for ever, and it shall be a faithful witness in heaven: i.e. "The moon shall be a faithful witness to this promise of God, so long as it continues in the heavens." See Mudge and Houbigant.
Related Commentaries of Psalms 89:35
Psalms 89:35
35 Once have I sworn by my holiness that I will not lie unto David.