In addition to everything else stated here, the Rambam in his introduction to the last chapter of Sanhedrin, where he develops his 13 foundations of Jewish belief, explains the immutability of the Torah as the 9th foundation, and quotes the verse "You shall not add onto [the Torah] or subtract from it" (Deuteronomy 13:1) as the source of this central belief.

In Yesodei HaTorah 9:1 the Rambam also brings this verse

דבר ברור ומפורש בתורה, שהיא מצוה עומדת לעולם ולעולמי עולמים: אין לה לא שינוי, ולא גירעון ולא תוספת, שנאמר "את כל הדבר, אשר אנוכי מצווה אתכם--אותו תשמרו, לעשות: לא תוסף עליו, ולא תגרע ממנו

 

הא למדת שכל דברי תורה, מצווין אנו לעשותן עד עולם

 

It is explicit in the Torah that it is an eternal law forever, not subject to change, neither subtractions or additions, as it says "All the matters which I have commanded you, keep it to do perform; do not add onto it nor subtract from it."

 

You have hereby learned that we are commanded to keep the entire Torah forever.

In addition to everything else stated here, the Rambam in his introduction to the last chapter of Sanhedrin, where he develops his 13 foundations of Jewish belief, explains the immutability of the Torah as the 9th foundation, and quotes the verse "You shall not add onto [the Torah] or subtract from it" (Deuteronomy 13:1) as the source of this central belief.

In Yesodei HaTorah 9:1 the Rambam also brings this verse

דבר ברור ומפורש בתורה, שהיא מצוה עומדת לעולם ולעולמי עולמים: אין לה לא שינוי, ולא גירעון ולא תוספת, שנאמר "את כל הדבר, אשר אנוכי מצווה אתכם--אותו תשמרו, לעשות: לא תוסף עליו, ולא תגרע ממנו

הא למדת שכל דברי תורה, מצווין אנו לעשותן עד עולם

It is explicit in the Torah that it is an eternal law forever, not subject to change, neither subtractions or additions, as it says "All the matters which I have commanded you, keep it to do perform; do not add onto it nor subtract from it."

You have hereby learned that we are commanded to keep the entire Torah forever.

In addition to everything else stated here, the Rambam in his introduction to the last chapter of Sanhedrin, where he develops his 13 foundations of Jewish belief, explains the immutability of the Torah as the 9th foundation, and quotes the verse "You shall not add onto [the Torah] or subtract from it" (Deuteronomy 13:1) as the source of this central belief.

In addition to everything else stated here, the Rambam in his introduction to the last chapter of Sanhedrin, where he develops his 13 foundations of Jewish belief, explains the immutability of the Torah as the 9th foundation, and quotes the verse "You shall not add onto [the Torah] or subtract from it" (Deuteronomy 13:1) as the source of this central belief.

In Yesodei HaTorah 9:1 the Rambam also brings this verse

דבר ברור ומפורש בתורה, שהיא מצוה עומדת לעולם ולעולמי עולמים: אין לה לא שינוי, ולא גירעון ולא תוספת, שנאמר "את כל הדבר, אשר אנוכי מצווה אתכם--אותו תשמרו, לעשות: לא תוסף עליו, ולא תגרע ממנו

הא למדת שכל דברי תורה, מצווין אנו לעשותן עד עולם

It is explicit in the Torah that it is an eternal law forever, not subject to change, neither subtractions or additions, as it says "All the matters which I have commanded you, keep it to do perform; do not add onto it nor subtract from it."

You have hereby learned that we are commanded to keep the entire Torah forever.