Справочник к Вайикра 19:23

And Ramban, may his memory be blessed, wrote about the reason for the commandment in his commentaries (Ramban on Leviticus 19:23) [that it is] to honor God, may He be blessed, from the beginning of all our produce, and not to eat from them until we bring all of the fruits of one year [as] 'praising to the Lord.' And behold, within the first three years, the fruit is not fit to offer, since it is meager; and also because [the tree] does not give taste or a good fragrance into its fruit [then]; also because most trees do not put out fruit at all until the fourth year from their planting - and so we wait for them all. And this commandment is similar to the first-fruits. And he also wrote that the truth of the thing is also that the fruit at the beginning of its planting until the fourth year is full of moisture that is very clingy, [which] injures the body and [so] is not good to eat; like the fish that have no scales, and the [other] foods prohibited by the Torah, which are bad also for the body.