Yea, they shall sing in the ways of the LORD: for great is the glory of the LORD.
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Augustine of Hippo
8. "And let them sing in the paths of the Lord, that great is the glory of the Lord" (ver. 5). Let all the kings of the earth sing in the paths of the Lord. In what paths? Those that are spoken of above, "in Thy mercy and Thy truth." Let not then the kings of the earth be proud, let them be humble. Then let them sing in the ways of the Lord, if they be humble: let them love, and they shall sing. We know travellers that sing; they sing, and hasten to reach the end of their journey. There are evil songs, such as belong to the old man; to the new man belongeth a new song. Let then the kings of the earth too walk in Thy paths, let them walk and sing in Thy paths, Sing what? that "great is the glory of the Lord," not of kings. ...