John Trapp on Psalms 42:8

Verſ. 8. Yet the Lord will command his loving kindneſs] He will after all this miſery ſend forth a Commiſſion, and a command to ſet me free: and his Mandamus will do it at any time.

And in the night his Song ſhall be with me] When others that are without God in the World have reſtleſs nights, the gnats of cares and griefs moleſting them, a Saint can ſing away care, and call his ſoul to reſt, as Pſal. 116.7. being filled with peace, and joy through beleeving; ſuch as ſetteth him a ſinging to Gods glory.

And my prayer unto the God of my life] i.e. My Praiſes, which are a chief part of prayer, 1 Tim. 26.1. Thankſ-giving is an artificial begging, Gratiarum actio eſt adplus dandum invitatio.