There are numerous instances of the beatitude form in the OT, as in the psalms (1; 32; 119), but the word is particularly applied to part of Jesus' Sermon on the Mount (Matt. 5–7) following his forty days' temptation in the wilderness. It opens with a series of beatitudes (blessings), which are essentially eschatological; that is, they are related to the arrival in Jesus of the kingdom of God. Disciples are blessed when they recognize this intervention of God: they may be living in this world; but under the pressure of the Kingdom, they reject the usual values of this world. Thus, ‘the poor in spirit’ are blessed—those who are unattracted to, indifferent to, money and possessions are blessed. Behind Matthew's narrative is the recollection of Moses receiving the Law on Mount Sinai. But it is placed firmly in a context of grace, not threats (Heb. 12: 20–21).
The beatitudes take a different form in Luke 6: 20–26, and the explicit mention that Jesus stood ‘on a level place’ (6: 17) seems to be making a deliberate contrast with Matt. 5: 1, since to be on level ground would not normally call for special notice. Luke loves to mention Jesus' compassion for the literally poor, the disadvantaged, the despised, and second-class citizens: so in Luke the first beatitude is ‘Blessed are you who are poor’, followed in 6: 24 by ‘But woe to you who are rich’.
There are also isolated beatitudes scattered through the gospels, and one is also quoted at Acts 20: 35.