Matthew 5:4 - Matthew Poole's English Annotations on the Holy Bible

The world is mistaken in accounting the jocund and merry companions the only happy men; their mirth is madness, and their joy will be like crackling of thorns under a pot: but those are rather the happy men, who mourn; yea, such are most certainly happy, who mourn out of duty in the sense of their own sins, or of the sins of others, or who mourn out of choice rather to suffer afflictions and persecutions with the people of God, than to enjoy the pleasure of sin for a season. Though such sufferings do excite in them natural passions, yet it is a blessed mourning, for those are the blessed tears which God will wipe at last from his people's eyes, and such are these. They shall be comforted, either in this life, with the consolations of the Spirit, or with their Master's joy in the life that is to come, Isaiah 61:3 1 Thessalonians 16:20 James 1:12. So as this promise, and declaration of blessedness, is not to be extended to all mourners, but only to such as God hath made so, or who in duty have made themselves so, obeying some command of God, for sympathizing with God's glory, or with his afflicted people, Romans 12:15, or testifying their repentance for their sins; for there is a mourning which is a mere natural effect of passion, and a worldly sorrow which worketh unto death, as well as a godly sorrow working repentance to salvation, 2 Corinthians 7:10.