Charles H. Spurgeon on Psalms 103:21

Bless ye the Lord, all ye his hosts; to whatever race of creatures ye may belong, for ye are all his troops, and he is the Generallissimo of all your armies. The fowl of the air and the fish of the sea, and whatsoever passeth through the paths of the sea, should all unite in praising their Creator, after the best of their ability. Ye ministers of his that do his pleasure; in whatever way ye serve him, bless him as ye serve. The Psalmist would have every servant in the Lord's palace unite with him, and all at once sing out the praises of the Lord. We have attached a new sense to the word "ministers" in these latter days, and so narrowed it down to those who serve in word and doctrine. Yet no true minister would wish to alter it, for we are above all men bound to be the Lord's servants, and we would, beyond all other ministering intelligences or forces, desire to bless the glorious Lord.