The Enchiridion 16 : 1

When you see anyone weeping for grief, either that his son has gone abroad or that he has suffered in his affairs, take care not to be overcome by the apparent evil, but discriminate and be ready to say, “What hurts this man is not this occurrence itself—for another man might not be hurt by it—but the view he chooses to take of it.” As far as conversation goes, however, do not disdain to accommodate yourself to him and, if need be, to groan with him. Take heed, however, not to groan inwardly, too.