The first and the second beatitudes in their order and terminology may reflect Isaiah 61: 1-3. Here part of the prophet’s mission to the poor is “to comfort all who mourn.”
The Lukan parallel to Matthew 5: 4 is worded somewhat differently: “Blessed are you that weep now, for you shall laugh” (Lk 6: 21). By using the word “mourn” instead of “weep” and by the word “comfort” instead of “laugh,” Matthew seems to tone down the physical aspect and emphasize the internal dimension of sorrow and grief. Whatever be the emphasis and whatever be the cause of mourning, Jesus, in the beatitude, promises a reversal of the situation for the mourners: “they shall be comforted.” The messianic era will bring comfort to the afflicted and grief-stricken people was already foretold by the prophets (Cf. Is 51: 3; 60: 20; 66: 10; Jer 31: 13). The comfort that Jesus promises to the mourners in this beatitude is a divine action. The passive form of the verb (“you shall be comforted”) implies that God is the agent, that God will comfort them. Although the messianic blessing of comfort is already a reality in the person and ministry of Jesus, in the beatitude it is spoken of as an end-time blessing when the fullness of salvation is revealed.