Psalms 89:5 - Matthew Poole's English Annotations on the Holy Bible

The heavens, i.e. the inhabitants of heaven, the holy angels, as Job 15:15; who clearly discern and constantly adore thy mercy and faithfulness, when men upon earth are filled with doubts and perplexities about it. Thy faithfulness also; understand, shall be praised, out of the foregoing clause; which supplements are most usual in Scripture, as hath been already showed by divers instances. In the congregation of the saints; either, first, Of thy saints upon earth in their public assemblies; who always acknowledge and celebrate thy truth, although they cannot always discern the footsteps of it. Or rather, secondly, Of the angels of heaven, of whom he speaks in the foregoing clause; who are oft called saints or holy ones, as Deuteronomy 33:2 Job 15:15 Daniel 4:13,17 Daniel 8:13.