לֹ֣א תֹסִ֗פוּ עַל־הַדָּבָר֙ אֲשֶׁ֤ר אָנֹכִי֙ מְצַוֶּ֣ה אֶתְכֶ֔ם וְלֹ֥א תִגְרְע֖וּ מִמֶּ֑נּוּ לִשְׁמֹ֗ר אֶת־מִצְוֺת֙ יְהוָ֣ה אֱלֹֽהֵיכֶ֔ם אֲשֶׁ֥ר אָנֹכִ֖י מְצַוֶּ֥ה אֶתְכֶֽם׃
Ye shall not add unto the word which I command you, neither shall ye diminish from it, that ye may keep the commandments of the LORD your God which I command you.
Find Mishnaic references to Deuteronomy 4:2: passages from the 63 tractates of the Mishnah that cite or discuss this verse, free.