James 2:10

For, whoever observes the entire law [of God] and yet breaks one requirement [of it], becomes guilty of [breaking] all of it.

Galatians 3:10

For all who seek to be right with God by trying to meet all the requirements of the law of Moses are under a curse [from God], because it is written [Deut. 27:26], "Every person is cursed [i.e., cut off from God] who does not continue to obey all of the requirements written in the law of Moses."

Matthew 5:18-19

For it is true when I say, not one little letter or even a portion of a letter will be removed from the law of Moses until everything is accomplished [that is required by them]. [When that happens, then] heaven and earth will pass away [i.e., be destroyed. See II Peter 3:12].

Treasury of Scripture Knowledge

Summary

For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.

Bible References

Whosoever

Matthew 5:18
For it is true when I say, not one little letter or even a portion of a letter will be removed from the law of Moses until everything is accomplished [that is required by them]. [When that happens, then] heaven and earth will pass away [i.e., be destroyed. See II Peter 3:12].
Galatians 3:10
For all who seek to be right with God by trying to meet all the requirements of the law of Moses are under a curse [from God], because it is written [Deut. 27:26], "Every person is cursed [i.e., cut off from God] who does not continue to obey all of the requirements written in the law of Moses."