Or HaChaim on Deuteronomy 26:2/אור החיים על דברים כ״ו:ב׳

1 מראשית, "of the first, etc." This means that if a number of fruits ripen all at the same time only some of them have to be offered under the heading of בכורים. Our sages in Bikkurim 1,6 who stated that only the seven species mentioned in Deut. 8,8 are the subject of this legislation, derived this by the exegetical tool called גזרה שוה, i.e. the Torah employing similar sounding words in two unrelated subject matters when one or both of these words are superfluous in their context. The word which gives rise to this halachah is the word ארץ in the verse we just mentioned. According to Menachot 84 the words כל פרי, "all the fruit," mean that just as in Deut. 8,8. the Torah enumerated the seven species for which the land of Israel is especially extolled, so the law of בכורים applies only to these species.

2אשר ה׳ אלוקיך נתן לך "which the Lord your G'd is about to give to you;" The Torah emphasises the part of the land that G'd gives to you, because He had reserved for Himself part of that land, i.e. every seventh year when you are not allowed to work the land (compare Leviticus 25,4). It states there specifically that during the seventh year the land reverts to being G'd's. The legislation of Bikkurim applies only during the six years the Israelite farms his land. Although the land produces a harvest also during the seventh year the legislation does not apply as the land does not then belong to the farmer but is officially "ownerless."