A search of the W/H Greek NT and the LXX for μακαρι%μακαριοι οτι using a tool like the Unbound BibleStep Bible, say, will reveal that the Beatitudes of Matthew 5 reveal a literary form that is particular, but not exclusive, to Jesus.
Blessed (μακαριοι) ... because (οτι) ...
The search is not exhaustive, of course, because verse boundaries prevent instances like Matthew 5:11-12 or Luke 10:23-24 being picked up, but it is sufficient to reveal Jesus' particular use of the form.
A search for instances of μακαρι%, alone, yields statements like Jesus uses in Luke 7:23 where the "because" is implicit.
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Blessed are the poor in spirit: for theirs is the kingdom of heaven.
Blessed are the poor in spirit: for theirs is the kingdom of heaven.
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Blessed are they that mourn: for they shall be comforted.
Blessed are they that mourn: for they shall be comforted.
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Blessed are the meek: for they shall inherit the earth.
Blessed are the meek: for they shall inherit the earth.