James 5:13

Is any among you afflicted?
&c.] As the people of God generally are; they are commonly a poor, and an afflicted people; at least there are many among them that are so, and many are their afflictions: those whom Christ loves, as he did Lazarus, are not free from sicknesses and diseases; and these are rather signs of love than arguments against it; and when this is the case of any of the saints, what is to be done?

let him pray;
to God that can save him; in the name of Christ; under the influence of the Spirit; believing in the word of promise. Times of afflictions are proper times for prayer; there is then more especially need of it; and God sometimes lays his afflicting hand upon his people, when they have been negligent of their duty, and he has not heard of them for some time, in order to bring them near to him, to seek his face, pay him a visit, and pour out a prayer before him; see ( Psalms 50:15 ) .

Is any merry?
in good heart and spirit, in a good frame of mind, as well as in prosperous circumstances, in soul, body and estate:

let him sing psalms;
let him not only be inwardly joyful, as he should be in prosperity, and be thankful to God for his many mercies, temporal and spiritual, he enjoys; but let him express it vocally, and melodiously, by singing psalms, hymns, and spiritual songs: not that these are the only persons that are to sing psalms, or this the only time, any more than that afflicted persons are the only ones that are to pray, or the time of affliction the only time of prayer; but as affliction more especially calls for prayer, so spiritual joy, and rejoicing in prosperous seasons, for singing of psalms: weeping, and singing of psalms, were thought, by the Jews, inconsistent. Kimchi, on the title of the third psalm, observes, that their Rabbins say, that when David went up the ascent of the Mount of Olives, he wept; and if he wept, why is this called a psalm? and if a psalm, (hkb hml) , "why did he weep?"