John Trapp on Psalms 103:20

Verſ. 20. Bleſs the Lord, ye his Angels] In ſtirring up the Angels to praiſe God, he awakeneth himſelf; and for this purpoſe, Incipit à ſuperioribus, & finit in infimis, ſaith Kimcbi here, he calleth in the help of all the creatures from the higheſt to the loweſt; and after all, concludeth as he began with a ſaying to himſelf.

That excel in strength] Heb. Giants for ſtrength, ſuch as can prevail, and do great exploits, yet is all their ſtrength derivative, they have it from God (who it Hagibbor, the Mighty One, Deut. 10.17.) and hence the Angel Gabriel hath his name, God is my ſtrength. Labour we to be like unto the Angels, ſtrengthened with all might &c. Col. 1.11. walking about the world as Conquerors, able to do all things through Chriſt who ſtrengthneth us, Philip. 4.13.

That do his Commandements] viz. Cheerfully, ſpeedily, univerſally, humbly, conſtantly. Let us do accordingly, elſe we mock God when we pray, Thy will be done in earth, as it is in heaven.