James 5:20 - Matthew Poole's English Annotations on the Holy Bible

Of his way; of his life and actions, which is contrary to the way which God hath prescribed. Shall save; men are said to save in the same way as to convert, viz. instrumentally. A soul; the soul of him that is thus converted, 1 Timothy 4:16: soul for person, as James 1:21. From death: eternal death, unto which he was hastening while he continued in the error of his way, which led him toward destruction. And shall hide a multitude of sins; in the same sense as before he is said to convert and save his soul, viz. in being instrumental to bring him to faith and repentance, upon which God pardons, i.e. hides his sins, \Psalms 32:1\ though not from the eye of his omniscience, yet from the eye of his vindictive justice, and so as not to bring them forth in judgment against him.