Matthew 5:4

Mourn. Greek penthed, denoting intense mourning, contrasting with lupeomai, “to grieve” (Matt. 14:9; 1 Peter 1:6). The profound spiritual poverty of the “poor in spirit” (v. 3) is matched by the deep mourning of those described here. It is a deep sense of spiritual need leading men to mourn their imperfection (MB 9; DA 300). Christ refers to those who long to reach perfection (Isa. 6:5; Rom. 7:24). The verse also comforts those mourning disappointment, bereavement, or sorrow (MB 10-12).

Shall be comforted. Greek parakaleo, “to call to the side,” “to call to aid,” “to exhort,” “to cheer,” “to console,” “to comfort.” A friend so summoned is a parakletos; Jesus is called a parakletos (1 John 2:1). He promised to send “another Comforter,” the Holy Spirit (John 14:16), to abide with us.

God meets spiritual need with grace (v. 3) and mourning over sin with the comfort of forgiveness. Mourning for sin is the second requirement for kingdom candidates, following the first step of recognizing need.