You shall not add to the word that I speak to you, neither shall you take away from it: keep the commandments of the Lord your God which I command you.

“לא תספו YE SHALL NOT ADD — For instance, to place five chapters in the Tephillin, to employ five species of fruit and plants in the fulfilment of the command of Lulab And to place five fringes on one’s garment. Thus, too, must we explain the following words ולא תגרעו, Ye shall not diminish [from it]" (Sifrei Devarim 82:4).”

“YE SHALL NOT ADD [UNTO THE WORD WHICH I COMMAND YOU] — “such as placing five sections [of the Torah] in the phylacteries, five species in a lulav, are: the palm-branch, the ethrog, the myrtle and the willows. — For phylacteries See Vol. II, p. 168, Note 406. five fringes [in a garment]. The same principle applies to the prohibition, neither shall ye diminish from it” [by placing three sections of the Torah in the phylacteries etc.]. This is Rashi’s language. And thus the Rabbis said in the Sifre: 82. “Whence do we know that you are not to add to [the four species in the commandment of] the lulav, are: the palm-branch, the ethrog, the myrtle and the willows. — For phylacteries See Vol. II, p. 168, Note 406. nor to the [four] fringes? Scripture therefore says, Ye shall not add. And whence do we know that you are not to diminish from them? Because Scripture states, neither shall ye diminish. Whence do we know that if [a priest] began to recite the Priestly Blessing he is not to say: ‘Since I began to bless [the people], I will [further] say, The Eternal, the G-d of your fathers, make you a thousand times so many more as ye are?’ Because Scripture states, [Ye shall not add] unto the ‘word’ — even ‘a word’ you are not to add to it.” However, not only concerning these [commandments] have the Rabbis said [that the prohibitions neither to add nor to diminish, apply], but also in the case of someone who sleeps in a Booth on the eighth Day [of the Festival of Tabernacles]. Thus the Torah specifically states that the commandment to dwell in Booths applies to seven days only, and not to the eighth Day, which is a separate festival (Shemini Atzereth). Sleeping is part of the commandment “to dwell” in a Booth. [However, because of the general rule that he who feels uncomfortable is exempt from sitting in a Booth, sleeping there, in the colder climates in which we live, is practiced only by those who are very strict in religious observance (Orach Chayim 639:2, R’ma).] with the intent [of performing a religious duty] that he is liable to whipping [for having added to the commandment], as is mentioned in Tractate Rosh Hashanah. So also if he were to observe the Festival of Tabernacles for only six days, he would be transgressing this negative commandment [neither shall ye diminish from it]. In my opinion, even if someone devised an independent commandment [rather than altering an existing one] such as establishing a festival in a month which he had devised of his own accord, as Jeroboam did, he transgresses the negative commandment [Ye shall not add unto the word which I command you]. And so did the Rabbis say with reference to the reading of the Scroll of Esther [on Purim]: “One hundred and eighty prophets arose in Israel and they did not diminish from nor add even one letter to what was written in the Torah, except for reading the Scroll of Esther [which was instituted by the prophets]. What basis did they have for that? etc.” (reasoning from minor to major): If [when Israel was delivered] from slavery to freedom they sang [in praise of G-d], how much more ought they to do so when they were saved from death [that was decreed upon Israel through the plot of Haman] to life!” (Megillah 14 b). The reading of the Scroll of Esther constitutes the praise to G-d for our deliverance (ibid.). And in the Yerushalmi it is stated: “Eighty-five elders, among them many prophets, were troubled about the matter [of the new duty to read the Scroll of Esther]. They said, ‘It is written, These are the commandments which the Eternal commanded Moses. These are the commandments that [we] were ordered by the mouth of Moses, and Moses told us that no other prophet is destined to establish anything new for you — and Mordecai and Esther want to establish something new for us!’ They did not move from there while discussing the matter, until the Holy One, blessed be He, enlightened their eyes [and they found the new commandment intimated in the Torah, Prophets, and Writings].” Thus you see that [the institution of] this commandment [of reading the Scroll of Esther on Purim] would have been forbidden to them [were it not for the fact that ultimately they found it intimated in the Torah, etc.]; otherwise it would have been included in the principle, thou shalt not add thereto. (613) Commandments, or of abolishing altogether one of the Divine precepts. In speaking, therefore, of the prophetic precept of reading the Scroll of Esther on Purim, Ramban thus rightly cites the verse from further on (13:1), for were it not that the prophets and Sages of that time found it intimated in the Torah, the prohibition against instituting such a new commandment would have come under the admonition, thou shalt not add thereto. However, the prohibition against adding [to the Torah] by word of a prophet we derive only from the verse stating, These are the commandments, which establishes,. “From now on, no prophet is permitted to originate anything [in the Torah].” Whatever [laws] the Sages have established in the nature of “a fence [around the Torah],” such as the secondary degrees of forbidden marriages — that activity of [establishing fences] is itself a requirement of the Torah, provided only that one realizes that these [laws] are a result of a particular fence and that they are not [expressly] from the mouth of the Holy One, blessed be He, in the Torah. (and ye shall keep My charge — Leviticus 18:30), tradition interpreting this to mean: “Make a mishmereth (a protection, a fence as a safeguard) l’mishmarti (for My commandment)” (Yebamoth 21 b).”

“Add any thing repugnant to the spirit of my law. No interpretation of this kind can be admitted. But this does not condemn well authorized traditions, and laws enacted by lawful superiors. The Jews always boast of their close adherence to the letter of the law, but they often forget the spirit of it, and by their traditions render it deformed, like a carcass. Demosthenes takes notice, that the Locrians had such a regard for their laws, that if any one chose to propose any fresh ones, he came with a rope about his neck, that if they did not meet with the approbation of the people, he might be strangled immediately. (Calmet) — Moses cannot mean to forbid any more divine or civil commandments being written by Josue and the subsequent prophets. He only enjoins that nothing shall be altered by human authority. The other books of the Old Testament serve to explain the law; and so do the apostolical traditions (Worthington) afford great assistance to understand the true meaning of all the Scriptures, and hence we learn whatever we have to perform, without danger of being led astray. (Haydock) — To these the Scriptures frequently refer. He that heareth you, heareth me, Luke x. Hold the traditions which you have learnt, 2 Thessalonians ii. The rest I will set in order, when I come, 1 Corinthians xi. 34. Hence St. Augustine (contra Cresc. i. 33) observes, “Though no evident example can be produced from Scripture, yet we hold the truth of the same Scripture, when we do what meets with the approbation of that Church whose authority the Scripture establishes.” See ep. 80, St. Chrysostom in 1 Thess. iv.; St. Irenĉus, Against Heresies iii. 4. (Worthington) — The Jews themselves never had the folly to imagine with the modern innovators, that all laws both of a religous or civil nature were here proscribed. Under David, Mardocheus, and the Machabees, various laws and feasts were commanded, and observed in the true spirit of the law, 1 Kings xxx. 25., and Esther ix., and 1 Machabees iv. God does not leave to the discretion of the Jews, the appointing of different victims, &c., in his worship, (chap. xii. 30,) as they might very easily give way to the superstitious observances of their neighbours, and these things had been sufficiently determined. But he enjoins all to obey the declarations of the priests and judges, chap. xvii. 10. (Bellarmine) (Tirinus) — Thus when the Apocalypse records a prohibition similar to this, (Apocalypse xxii. 18, 19,) it is not intended to seal up the divine volume, so that nothing more shall be admitted into it, for St. John wrote his gospel afterwards. But it must be explained in the same sense as this passage, and condemns all those who, of their own authority, would set up fresh doctrine in opposition to the word of God. Let Protestants consider if they be not concerned in this caution, when they not only cut off whole books of Scripture, but deny the authority of the Church itself, without which the Scripture can be of little service. They are the book sealed with seven seals, impenetrable to man without the aid of the divine author; (Apocalypse v. 5,) and this aid he will never grant to those who obstinately refuse to hear the Church, Matthew xviii. 17., and 2 Peter i. 20. (Haydock)”

“The life here promised seems to be temporal. By fulfilling the commandments the Israelites escaped death, which was the penalty attached to transgrelsion. Eternal life likewise was the reward of obedience grounded on faith. Although It was from the beginning the object of hope, and the primary motive of worship and obedience, it was not prominently held forth under the law, which was directed to the government of the people and their social organisation. a The truths taught by Moses were to be preserved without change : the laws which he delivered were to be inviolably observed. In worshipping God the Hebrews were to follow the Divine prescription, with- out neglecting or changing anything that was commanded. Grotius remarks that this passage is not in opposition with those who interpret Scripture by tradition, and protect the law by special enactments. To add, he says, is to do otherwise than is prescribed : to take away, is to neglect fulfilling what is com- manded.”

“Ye shall not add unto the word which I command you--by the introduction of any heathen superstition or forms of worship different from those which I have appointed (Deu 12:32; Num 15:39; Mat 15:9). neither shall ye diminish aught from it--by the neglect or omission of any of the observances, however trivial or irksome, which I have prescribed. The character and provisions of the ancient dispensation were adapted with divine wisdom to the instruction of that infant state of the church. But it was only a temporary economy; and although God here authorizes Moses to command that all its institutions should be honored with unfailing observance, this did not prevent Him from commissioning other prophets to alter or abrogate them when the end of that dispensation was attained.”