Mat 5:7 Blessed are the merciful: for they shall obtain mercy.
Lucky are those who are full of pity, for they will be shown pity.
The Greek here is only five words. Like most of the beatitude, it is much shorter than the translations. There are a number of patterns in the Beatitudes, which are discussed in this article on the Beatitudes. The first four Beatitudes focus on various focus on how various forms of want create advantages. The last four focus on how various advantages create advantages.
In the previous verses, we have looked at how the sense of the Greek word translated as "blessed" shifts its meaning among "happy", "wealthy", and fortunate depending on the context. "Fortunate or lucky seems to work here. This word only means "blessed" in the sense that the lucky are blessed by good fortuned. It is not a religious term.
There is no "is" here. It is added to make a written sentence as opposed to a spoken phrase.
The key Greek word here means "having mercy" and "having pity." The first use of this word is in its adjective form, used as a noun. The second use is the verb form in the passive form, that is, "being the object of mercy or pity."
The "for" here is a causal adverb that means "seeing that", "because", or "since."
The "they" is used explicitly as the subject of the final phrase. This is unnecessary in Greek because the subject is also a part of the verb ending. Christ only uses the pronoun when he wants to emphasize it.
Again, our modern ideas of mercy or pity are not the same as the Greek concepts. In Greek, the concept is largely involved with the private system of debts: who owes what to whom. This was the organizing force in private society in a world where government control was largely a matter of the power to tax.
This idea of the importance of debt in Christ's society is largely erased in the translation of the Bible. For example, conceptually, this line repeats the formula from the Lord's Prayer, "Forgive us our sins as we forgive those who sin against us." This connection is obscured by the translation of "forgive" and "sin" and our modern ideas of mercy. Though it is easy to get to the idea of "those who show merciful will receive mercy," in Greek, the connection is closer, "one who lets go of other's debts will have their debts dropped."
Another thing we should notice is that this Beatitude, as in them all, the "they" is used explicitly as the subject of the final phrase. This is unnecessary in Greek because the subject is also a part of the verb ending. Christ only uses the pronoun when he wants to emphasize it.
A repetition of the same word expressing the idea of one who has something, mercy, will need what they currently have, that is, mercy.
The Spoken Version:
The speaker returned the wineskin to its owner. Meanwhile, the foreign women started passing out bread to some nearby children.
“Lucky,” he said, indicating these women. “Are those who are merciful.”
Again, the Militants made complaining noises.
“Because,” he said, indicating again both the foreigners and the Militants. “They themselves are going to receive mercy.”
ὅτι (adv) "For" is from hoti, which means "for what," and "wherefore." A form of hostis (hostis), which means "that", "anyone who", "anything which", "whosoever," "whichsoever" and "anybody whatsoever."
αὐτοὶ (adj pl masc nom) "They" is from autos, which means "the same," and the reflexive pronouns, "myself", "yourself", "himself", "herself", "itself," or the oblique case of the pronouns, "him", "her," and "it." It also means "one's true self," that is, "the soul" as opposed to the body and "of ones own accord."
ἐλεηθήσονται. (3rd pl fut ind pass) "Mercy" is from the verb eleeo, which means "to have pity on," "to show mercy to," and "to feel pity." In the passive, "to be shown pity," and "to be pitied." (Here in the future, passive, indicative form.)