Note 5 at Mt 5:4: Jesus could have been referring to those who mourn because of their problems. Isa 61:1-3 definitely states that the Christ would comfort those who mourn (2Co 1:3-4). He could have also been identifying the repentant person, as in 2Co 7:9-11 and Jas 4:9. Or He could have been speaking to "all that mourn" (Isa 61:2), which would include both of these groups.