Deuteronomy 26:12-15 states:
When you have set aside in full the tenth part of your yield-in the third year, the year of the tithe-and have given it to the Levite, the stranger, the fatherless, and the widow, that they may eat their fill in your settlements, you shall declare before the L-rd your God: “I have cleared out the consecrated portion from the house; and I have given it to the Levite, the stranger, the fatherless and the widow, just as You commanded me; I have neither transgressed nor neglected any of Your commandments: I have not eaten of it while in mourning; I have not cleared out any of it while I was unclean, and I have not deposited any of it with the dead. I have obeyed the L-rd my God; I have done just as You commanded me. Look down from Your holy abode, from heaven, and bless Your people Israel and the soil You have given us, a land flowing with milk and honey, as You swore to our fathers.

According to Hazal, and most classical commentators, the declaration of vidui ma‘aserot that the Torah discusses encompasses all the tithes from the entire three year period before the recitation. (In his Mishneh Torah, the Rambam records the halakhot of vidui ma‘aserot in Sefer Zera‘im, chapter 11 of Hilkhot ma‘aser sheni ve-neta reva‘i.) The “consecrated portion,” accordingly, refers to ma‘aser sheni ve-neta reva‘i, which halakhically are considered holy (qadosh). Don Isaac Abravanel, on the other hand, claims that according to the simple peshat of the biblical verse (in the third year, the year of the tithe), the declaration exclusively concerns the “poor tithe” (ma‘aser ‘ani), in which one gives a tithe to the poorest people among Israel, and which is given davka in the third (and sixth) year of the seven-year shemittah cycle. (See Eric Lawee, Isaac Abarbanel’s Stance Toward Tradition: Defense, Dissent and Dialogue [Albany, New York, 2001], p. 213.) Abravanel claims that there is a special need for a declaration with respect to ma‘aser ‘ani. As opposed to ma‘aser sheni, one may not eat any of it but must give it all away to charity.

According to Abravanel, how could the Torah use the phrase “consecrated portion?” Halakhically, ma‘aser ‘ani possess no holiness, no qedushah! R. David Zvi Hoffman, z”l, in his commentary on Sefer Devarim, suggests that as the two tithes explicitly mentioned in Deuteronomy are ma‘aser sheni (in Parashat Re’eh; Deut. 14-22ff.) and ma‘aser ‘ani (in Parashat Ki Tavo), and as ma‘aser sheni possesses qedushah, and ma‘aser ‘ani is given in the third and the sixth year of every shemittah cycle in lieu of ma‘aser sheni, it is indeed legitimate to use the phrase, the consecrated portion, denoting qedushah, for ma‘aser ‘ani as well. (Perhaps there is a musar haskel here as well. Tzedaqah, in this view, is indeed a matter of holiness. Thus, it is legitimate to call the object that is given as tzedaqah qodesh: that is, “consecrated.”)

Looking at the relationship between ma‘aser ‘ani and the other terumot u’ma ‘aserot we are naturally led to analyze the reason for these commandments. It is clear that ma‘aser ‘ani is quintessentially a mitzvah bein adam la-havero, a command to help the neediest in society. What about the other terumot u’ma‘aserot?

In his Mishneh Torah, Rambam classifies all hilkhot terumot u-ma‘aserot in Sefer Zera’im, the Book of Agriculture (or, more literally, the Book of Seeds). (The Book contains seven subsections: Hilkhot Kilayim, Hilkhot Mattenot ‘Anniyim, Hilkhot Terumot, Hilkhot Ma‘aserot, Hilkhot Ma‘aser Sheni ve-Neta Reva‘i, Hilkhot Bikkurim u-She ‘ar Mattenot Kehunah she-bi-Gevulin, and Hilkhot Shemittah ve-Yovel.) The first five chapters of Hilkhot Mattenot ‘Aniyyim discuss other agricultural gifts to the poor; namely, leqet. shikhah and pe’ah, which are left on the field for the poor at the time of harvest. He devotes the sixth chapter of Hilkhot Mattenot ‘Aniyyim to the topic of ma‘aser ‘ani. Most famously, Rambam, in chapter seven, leaves the specific topic of agricultural gifts and discusses the general commandment to give charity to a poor person, a topic he continues to discuss for four chapters, culminating in his famous list (at the end of chapter 10) of the eight levels of charity.

It is clear then, that according to the Rambam, the mitzvoth of terumot u-ma‘aserot are interwoven with the mitzvah to give charity, tzedakah.

Rambam expresses this notion even more clearly in the Guide of the Perplexed, where he explicitly ties this notion to all the terumot u’ma‘aserot.

The commandments …included in the Book of Seeds of our compilation….If you consider all these commandments one by one, you will find that they are manifestly useful through instilling pity for the weak and the wretched, giving strength in various ways to the poor, and inciting us not to press hard upon those in straits and not to afflict the hearts of individuals who are in a weak position.

As for gifts to the poor, their meaning is manifest. The reason for the offerings (terumot) and the tithes is similarly manifest. Because he has no portion or inheritance with you (Deut. 14:29). You know the reason for this: so this tribe as a whole should be devoted exclusively to the divine service and to knowing the Law and should not be engaged in tilling and harvesting, but should be concerned exclusively with God, as it says: They shall teach Jacob Your judgments, and Israel Your Torah (Deut. 33:10). You will find that the text of the Torah speaks in several passages of the Levite and the stranger and the orphan and the widow; for it always considers (the Levite) as one of the poor in view of the fact that her has no property.
As for the second tithe, it is commanded that it should be spent exclusively on food in Jerusalem. For this leads of necessity to giving some of it in alms; for as it could only be employed on nourishment, it was easy for a man to have others have it little by little. Thus it necessarily brought about a gathering in one place, so that brotherhood and love among the people were greatly strengthened. (Guide III:39, Pines ed., pp. 550-51).

In sum, according to the Rambam, all the terumot u’maaserot are indeed expressive of the qiyyum ha-mitzvah of tzedaqah, of acts of kindness to those in need. Indeed, one can say that the ma‘aseh ha-mitzvah, the act of giving all terumot u’ma ‘aserot entails the qiyyum ha-mitzvah, the inner fulfillment, of tzedakah.

R. Prof. Yitzhak Twersky, z”l, suggested that in light of the Rambam’s remarks in the Guide, we can understand the superscription that the Rambam gave at the beginning of the Book of Agriculture in Mishneh Torah. He cites Psalm 119:173: Lend Your hand to help me, for I have chosen Your precepts. Why did Rambam cite davka this verse? What the Rambam was doing, he suggested, was incorporating his understand of these mitzvoth as he explained them in the Guide. “…aside from an alliterative connection between Zera’im and ‘ozreni, seems to reflect a special interpretation of pikkudim (precepts) as rational laws which promote social well-being. (See Isadore Twersky, Introduction to the Code of Maimonides [Mishneh Torah] [New Haven and London, 1980], p. 266.)

The institutions of terumot u’ma‘aserot are examples of such rational pikkudim. And when, at the close of vidui ma ‘aserot, we ask God to Look down from Your holy abode, from heaven, and bless Your people Israel and the soil You have given us, a land flowing with milk and honey, as You swore to our fathers (Deut 26:15), we are asking God to be charitable to us just as we have been charitable to others more needy than ourselves.