Rashi, Deuteronomy 26:2

of the first but not all the first, because not all fruits are subject to [the mitzvah of] “firstfruits”-only the seven species [for which the land of Israel is noted]. Here, in our verse, it says the word , “land,” and there [in the verse describing the praise of Eretz Israel], it says,“A land ( ) of wheat and barley, vines and figs and pomegranates, a land of oil-producing olives and honey” (Deut. 8:8). Just as the earlier verse (Deut. 8:8) is referring to the seven species through which Eretz Israel is praised, here too, [the verse is dealing with] the praise of the Land. [Rashi proceeds to explain two expressions in Deut. 8:8, which are relevant to the mitzvah of firstfruits, in light of the connection taught by our Rabbis above:] oil-producing olives [refers to]“ olives,” [see Sifrei 26:2, meaning superior quality] olives that retain their oil, keeping it gathered ( ) [as it were] inside it. [Hence, it is the superior fruits which must be brought here]. — [Ber. 39a] [And in the same verse (Deut. 8:8):] honey That is the honey of dates. — [Sifrei 26:2] of the first [of all the fruit] [What is the process of taking these fruits?] A man goes down into his field and sees a fig that has ripened. He winds a reed around it for a sign and declares:“This is the firstfruit ( )."- [Mishnah Bikkurim 3:1] [translation by Judaica Press]