Mat 5:33 Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:
Again, you all have heard that it was proclaimed to the ancients, you might not recant. You are going to give back to the Lord the promises of yours.
This verse contains a transition from a plural "you" in the opening phrase to a singular "you" in the quote. This is hidden in English. This often indicates a transition from Christ speaking to the audience to speaking an individual but, because Christ is quoting others here, following the pattern in the OT which was actually quoted in Mat 5:21. This indicates a sense of individual responsibility. Notice, however, that again Christ is not quoting the Old Testament. This is not the second commandment Exd 20:7, ("taking the Lord's name in vain") the eighth commandment, Exodus 20:16 (swearing falsely against your neighbor"), or even Lev 19:12 of "swearing by the [Lord's] name falsely." In the Septuagint, the Greek OT, a different word is used for "to swear" in all of these verses. This was most likely an oral teaching, what Christ calls elsewhere, "the teaching of men" (Mat 15:9). Christ also attacks his opponents for their rules for swearing in Mat 23:16.
The first phrase of this verse duplicates the beginning of Mat 5:21, with the addition of the initial word, "again." The "again" is a reference to this earlier verse.
The Greek verb translated as "ye have heard" means "hear of", "hear tell of", and "understand."
The Greek verb translated as "it hath been said" is not one of the common words for "said" or "tell", but a special one that means something more like "proclaim". It is in the passive here, "it has been proclaimed". However, Christ often uses more unusual words for humorous effect, which seems to the case here.
The word translated as "By them of old time" is an adjective used as a noun. It means "from the beginning" as an adjective and, as a noun, "the ancients." It is in the form of that usually means "to the ancients," but which can mean "by the ancients". The latter seems the most likely.
The Greek word translated as "not" is the Greek negative used to deny objective facts, not opinions. It makes a negative statement of fact. Adding "really" to the sentence to captures the same idea.
The Greek word translated as "Thou shalt... forswear thyself," specifically means "to swear falsely', "recant", or "renege" on a promise. Its meaning is literally "against oath". Its root word is the same as the noun translated later in this verse as "oath".
The Greek word translated as "but" joins phrases in an adversarial way. Since it always falls in the second position, translating it as "however" often captures its feeling better. When used in writing, it creates complex sentences, but when spoken, it makes a good pausing point so that an important or humorous word can follow.
The Greek word translated as "shalt perform" doesn't mean that at all. It means 'to give back" or, more precisely "to give from." However, in referring to information, like an oath, it means "to explain" or "to give an account". It is in the future tense. Again, this idea has much more of a sense of debt in the Greek of the era than it does in English. This could also be a reference to the practice condemned in Mat 23:16 of requiring oaths to be taken on the gold of the temple or gifts on the altar.
This debt is owed to "the Lord" or "the Master" a word used to refer to God. It is in the form of an indirect object.
What is given back? the Greek word means "the object upon which is sworn," only secondarily, it means the oath or vow. So, the idea is that, if you take an oath on your eyes, for example, you must give your eyes back to the Lord if you swear falsely. The Lord collects the debts created by swearing. This idea is important in understanding the following verses about taking oaths.
The Spoken Version:
The another woman complained loudly, “Marriage is the one promise that people can cancel with a note.”
The speaker responded more playfully. “Again, you have all heard tell that it was proclaimed by the ancients.” He then pretended to unroll another scroll. “‘Do not renege on a promise,” he read in his old man’s voice. Wagging his finger, he screeched a common line used by the Dedicated to shame people, “You each are going to give back to the Lord—those promises of yours.”
ἠκούσατε (2nd pl aor ind act ) "Ye have heard" is from akouo, which means "hear of", "hear tell of", "what one actually hears", "know by hearsay", "listen to", "give ear to", "hear and understand," and "understand."
ὅτι (conj) "That" is from hoti, which introduces a statement of fact "with regard to the fact that", "seeing that," and acts as a causal adverb meaning "for what", "because", "since," and "wherefore."
ἐρρέθη (3rd sg aor ind pass) "It hath been said," is from ero, which means "to speak", "to say", "to pronounce", "to tell", "to let suffice", "to announce", "to proclaim," (in passive) "to be pronounced", "to be mentioned", "to be specified", "to be agreed," and "to be promised."
τοῖς ἀρχαίοις (adj pl masc dat) "By them of old time" is from archaios, which means as an adjective means "from the beginning", "from the source", "ancient", "simple", "silly", "former", "the Ancients [of people]", "anciently [adverb], and "the principle [in a loan],"
Οὐκ (adv) "Not" is from ou which is the negative adverb for facts and statements, negating both single words and sentences. The other negative adverb, μή applies to will and thought; οὐ denies, μή rejects; οὐ is absolute, μή relative; οὐ objective, μή subjective.
ἐπιορκήσεις, (2nd sg aor subj act ) "Thou shalt...forswear thyself," is from epiorkeo, which means "to swear falsely," and "to forswear oneself." To "forswear" means "to recant" or "to renege" on a promise.
“ἀποδώσεις” (2nd sg fut ind act) "shalt perform" is from apodidomi which means "to give back", "to restore," and "to deliver." It also means to "give an account" of a thing, "explain", or "interpret." It has the economic sense of "to sell" or "to give something for one's own profit." It begins with apo the preposition of separation and origin, the idea of "from" in English, didômi which means "to give", "to grant", "to hand over," and "to describe."
δὲ (partic) "But" is from de which means "but" and "on the other hand." It is the particle that joins sentences in an adversarial way but can also be a weak connective ("and") and explanation of cause ("so") and a condition ("if").
“τῷ κυρίῳ (noun sg masc dat) "The Lord" is from kurios, which means "having power", "being in authority" and "being in possession of." It also means "lord", "master of the house," and "head of the family."