Rejoice with those who rejoice, etc. A general truth is in the third place laid down, -- that the faithful, regarding each other with mutual affection, are to consider the condition of others as their own. He first specifies two particular things, -- That they were to "rejoice with the joyful, and to weep with the weeping." For such is the nature of true love, that one prefers to weep with his brother, rather than to look at a distance on his grief, and to live in pleasure or ease. What is meant then is, -- that we, as much as possible, ought to sympathize with one another, and that, whatever our lot may be, each should transfer to himself the feeling of another, whether of grief in adversity, or of joy in prosperity. And, doubtless, not to regard with joy the happiness of a brother is envy; and not to grieve for his misfortunes is inhumanity. Let there be such a sympathy among us as may at the same time adapt us to all kinds of feelings.

Rejoice with them - This command grows out of the doctrine stated in Romans 12:4-5, that the church is one; that it has one interest; and therefore that there should be common sympathy in its joys and sorrows. Or, enter into the welfare of your fellow-Christians, and show your attachment to them by rejoicing that they are made happy; compare 1-Corinthians 12:26, "And whether. one member be honored, all the members rejoice with it." In this way happiness diffuses and multiplies itself. It becomes expanded over the face of the whole society; and the union of the Christian body tends to enlarge the sphere of happiness and to prolong the joy conferred by religion. God has bound the family of man together by these sympathies, and it is one of the happiest of all devices to perpetuate and extend human enjoyments.
Weep - See the note at John 11:35. At the grave of Lazarus our Saviour evinced this in a most tender and affecting manner. The design of this direction is to produce mutual kindness and affection, and to divide our sorrows by the sympathies of friends. Nothing is so well suited to do this as the sympathy of those we love. All who are afflicted know how much it diminishes their sorrow to see others sympathizing with them, and especially those who evince in their sympathies the Christian spirit. How sad would be a suffering world if there were none who regarded our griefs with interest or with tears! if every sufferer were left to bear his sorrows unpitied and alone! and if all the ties of human sympathy were rudely cut at once, and people were left to suffer in solitude and unbefriended! It may be added that it is the special duty of Christians to sympathize in each other's griefs:
(1) Because their Saviour set them the example;
(2) Because they belong to the same family;
(3) Because they are subject to similar trials and afflictions; and,
(4) Because they cannot expect the sympathy of a cold and unfeeling world.

Rejoice with them that do rejoice - Take a lively interest in the prosperity of others. Let it be a matter of rejoicing to you when you hear of the health, prosperity, or happiness of any brother.
Weep with them that weep - Labour after a compassionate or sympathizing mind. Let your heart feel for the distressed; enter into their sorrows, and bear a part of their burdens. It is a fact, attested by universal experience, that by sympathy a man may receive into his own affectionate feelings a measure of the distress of his friend, and that his friend does find himself relieved in the same proportion as the other has entered into his griefs. "But how do you account for this?" I do not account for it at all, it depends upon certain laws of nature, the principles of which have not been as yet duly developed.

Rejoice with them that do rejoice,.... Not in anything sinful and criminal, in a thing of nought, in men's own boastings; all such rejoicing is evil, and not to be joined in; but in things good and laudable, as in outward prosperity; and to rejoice with such, is a very difficult task; for unless persons have a near concern in the prosperity of others, they are very apt to envy it, or to murmur and repine, that they are not in equal, or superior circumstances; and also in things spiritual, with such who rejoice in the discoveries of God's love to their souls, in the views of interest in Christ, and of peace, pardon, and righteousness by him, and in hope of the glory of God; when such souls make their boast in the Lord, the humble hearing thereof will be glad, and will, as they ought to do, join with them in magnifying the Lord, and will exalt his name together:
and weep with them that weep; so Christ, as he rejoiced with them that rejoiced, at the marriage in Cana of Galilee, wept with them that wept, with Mary at the grave of Lazarus. The design of these rules is to excite and encourage sympathy in the saints with each other, in all conditions inward and outward, and with respect to things temporal and spiritual; in imitation of Christ their great high priest, who cannot but be touched with the infirmities of his people; and as founded upon, and arising from, their relation to each other, as members of the same body; see 1-Corinthians 12:26;

Rejoice with them that rejoice; and weep--the "and" should probably be omitted.
with them that weep--What a beautiful spirit of sympathy with the joys and sorrows of others is here inculcated! But it is only one charming phase of the unselfish character which belongs to all living Christianity. What a world will ours be when this shall become its reigning spirit! Of the two, however, it is more easy to sympathize with another's sorrows than his joys, because in the one case he needs us; in the other not. But just for this reason the latter is the more disinterested, and so the nobler.

Rejoice - The direct opposite to weeping is laughter; but this does not so well suit a Christian.