It is worthy of remark, how jealous the LORD is of his name and glory; in both Testaments of Scripture the precept of neither adding to, nor diminishing from, is strongly formed. See Revelation 22:18-19.
Related Commentaries of Deuteronomy 4:2
Deuteronomy 4:2
2 Ye shall not add unto the word which I command you, neither shall ye diminish ought from it, that ye may keep the commandments of the LORD your God which I command you.