Leviticus 23:40

And of your own shall you take on the first day of the feast, the fruits of praiseworthy trees, citrons, and lulabin, and myrtles, and willows that grow by the brooks; and you shall rejoice before the Lord your God seven days.

you shall lift up for yourselves We translate according to the words of the Exegetes — since they do not contradict the plain meaning of Scripture — even though elsewhere we translate “every man shall acquire for himself a lamb, for the family group” [Exodus 12:3]. The Exegetes have also transmitted to us the tradition that the fruit of the hadar tree denotes the citron, and, in truth, there is no tree with fruit more beautiful [Hebrew: hadar]. They also called it “the fruit that resides [Hebrew: haddar] on its tree” as a kind of mnemonic [Sukka 35a], as I have explained above concerning the passage “to other people” [Exodus 21:8] [the reference is to an earlier commentary on Exodus, known as the Perush Haqqaṣar — Translator]. The Sadducees [a derogatory reference to Karaites — Translator] have said that the Sukka must be built from these four species, bringing a proof from Ezra’s book [Nehemiah 8:15]. Didn’t these half-wits notice that no mention is made there of the brook-willow , nor of any kind of fruit? On the contrary, it is only a list of branches from five kinds of trees (the fact that “myrtle branches” are mentioned separately from “thick-tree branches” [Nehemiah 8:15] poses no problem to the traditional interpretation; there are two varieties — one tall and one short — and there the term “myrtle” denotes the short variety).

AND YE SHALL TAKE YOU ON THE FIRST DAY ‘PRI EITZ HADAR’ (THE FRUIT OF GOODLY TREES). “[That is, a tree] whose bark has the same taste as its fruit. Hadar [a fruit] that ‘remains’ on its tree from one year to another, and this is the ethrog.” This is Rashi’s language. But these interpretations are merely Scriptural supports which our Rabbis taught as a basis for their tradition [that the reference here is to the ethrog]. And Rabbi Abraham ibn Ezra wrote: “And they [i.e., the masters of tradition] have said the truth [that pri eitz hadar refers to the ethrog], for there is no fruit of the tree more beautiful (hadar) than the ethrog. The Rabbis’ interpreted that hadar means [the fruit] that ‘remains’ on its tree [from one year to another], but this is merely a Scriptural support for a matter of tradition.”
The correct interpretation appears to me to be that the tree which is called in the Aramaic language ethrog, is called in the Sacred Tongue hadar, for the meaning of the word ethrog is “desirable,” as [Onkelos] rendered: ‘nechmad’ (pleasant) to the sight —” dimrageig to see; “‘lo thachmod’ (Thou shalt not covet) — “thou shalt not theirog.” is given as the translation of the Hebrew ‘lo thithaveh’ (Thou shalt not desire) — in Deuteronomy 5:18. In Exodus 20:14, the Aramaic is the same as the Hebrew: lo thachameid. — The general point, however, is clearly established, that the term theirog means “desire,” “delight” or “pleasant.” The name ethrog is related to this expression. And we also say: “from all the best, arag (most desirable) properties.” And the terms hadar and chemdah are alike in meaning [“desirable”]. Thus the tree and the fruit [ethrog] are both called by one name [as hadar in Aramaic is ethrog], for such is the customary usage of names for most fruits: t’einah [denotes both the fig tree and the fruit]; egoz (nut); rimon (pomegranate); zayith (olive) and other fruits [in all of which cases both the tree and its fruit have the same name], and similarly this tree and fruit are both called in Aramaic ethrog, and in the Sacred Tongue they are called hadar.
In line with the plain meaning of Scripture the verse is stating that we should take for ourselves a pri eitz hadar [“the fruit of a tree …

וענף עץ עבות, the vowel kametz under the letter ע in the word עבות is similar to the same vowel in the word kadosh, קדוש or tahor, טהור, or amok, עמוק, i.e. a branch of a tree which possesses dense foliage.

ולקחתם לכם, “you shall take for yourselves, etc.” the sages explain the word לכם here as equivalent to מלכם, “from something that is yours;” these plants must neither be stolen or borrowed. If they were not legally yours, they would act as accusers rather than as advocates on your behalf. Tanchuma section 18 on this verse illustrates by the following parable: The king sent out one of his officers to collect taxes due to him. The officer proceeded to this but was waylaid on the way after having collected a considerable sum, and he was robbed both of his and of the king’s money. Some time later that same robber showed up at the entrance of the king’s palace where the official who had been robbed by him stood guard. He enquired what brought this man to the palace and was told that he had a problem that he wished to submit to the king’s judgment and he begged the official to support his request, or to hire someone to do so. He was then told by that official that as long as he had not made restitution for what he had stolen from him, there could be no question of his receiving any assistance. Thereupon the thief returned what he had stolen from this official. When on the morrow the erstwhile thief submitted his case to the king, the king asked him if he had anyone who could support his request. The petitioner pointed to the official and suggested that he could give testimony as to his character. When the king heard this, he turned to that official and asked him what he could have to say in favour of the petitioner. So the official proceeded to tell the king all that had happened between him and the petitioner. He pointed to some of the vessels that he had been robbed of, and which had been the king’s property originally and which had been returned to him on the understanding that he, this official, would plead on the petitioner’s behalf. All the people present then joined in saying: “woe to the accuser and woe to the accused who both have changed their role.”