Deuteronomy 4:1-2 defines Guarding The Word of God:
1“And now, O Yisra’ĕl, listen to the laws and the right-rulings which I am teaching you to do, so that you live, and shall go in and possess the land which יהוה Elohim of your fathers is giving you.
2“Do not add to the Word which I command you, and do not take away from it, so as to guard the commands of יהוה your Elohim which I am commanding you.
Interesting side note: Do you see how guarding the the commands of God are so heavily linked to entering into His Kingdom?