The arba minim – the four species which we are obligated to hold and wave each day of Sukkot – are arranged with the hadasim and aravot bound to the lulav branch, while the etrog is held separately from those three species. The Gemara in Masekhet Sukka (37b) establishes that one should hold the lulav – together, of course, with the hadasim and the aravot – in his right hand, and the etrog in his left. The reason, the Gemara explains, is that the more prominent hand – the right hand – should be used for three mitzvot – the lulav, the hadasim and the aravot – whereas the left, which is less prominent, for the single mitzva of the etrog.
The Magen Avraham (651:6) raises the question of why the Gemara found it necessary to explain why the lulav should be held in the right hand. When fulfilling the mitzva of arba minim, we recite the berakha of “al netilat lulav” – specifying the lulav. And the Shulchan Arukh (O.C. 206:4) rules that whenever one recites a berakha over a piece of food, a beverage, or something fragrant which he smells, he must hold the item in his right hand. Seemingly, this halakha should extend to the berakha over the lulav. Since – for reasons which lie beyond the scope of our discussion – we recite the berakha specifically over the lulav, it should naturally follow that we must hold the lulav in our right hand as we recite the berakha over this mitzva. Why, then, did the Gemara find it necessary to resort to the reason that the lulav includes three mitzvot, whereas the etrog is just one mitzva?
The Magen Avraham offers two answers to this question. First, he suggests that the Gemara here also addresses the more basic question of why we hold the lulav and etrog in separate hands, rather than holding them both in the same hand. Since all four species are included in the mitzva, it would seem appropriate to hold all of them together, in the more prominent hand. The answer is that the Torah, in formulating this command, appears to set the etrog apart from the other three species, as it links the other three species with the conjunction “ve-” (“and”; “kapot temarim va-anaf eitz avot ve-arvei nachal”). Once the Torah indicates that the etrog should be held separately from the other three, it stands to reason that the other three should be held in he right hand, given the prominence associated with the right side.
The Magen Avraham then proceeds to offer what appears to be a far simpler and more convincing answer, noting that Halakha requires holding the three other species in the right hand even when no berakha is recited. If one takes the four species later in the day, after having already fulfilled the mitzva (such as when one takes the four species for the hoshanot prayer), he does not recite the berakha, since the mitzva had already been fulfilled. If the reason for holding the lulav in the right hand was due solely to the requirement regarding the recitation of berakhot, then it would not apply in cases when no berakha is recited. The Gemara therefore presented an additional reason to explain why the lulav is always held in the right hand, even when no berakha is recited.