Hebrews 12:20

For those people could not stand [hearing] the command [Ex. 19:12f], "If even an animal touches the mountain, it must be stoned [to death]."

Romans 3:19-20

Now we [all] know that everything the law says applies to those who are under [obligation to obey] that law, [Note: Here "the law" appears to refer to the Old Testament Scriptures generally, since Psalms and Isaiah are quoted. See verses 10-18]. This is so that the mouth of every objector may be stopped [i.e., from making excuses for his sin], and thereby bring the entire world under God's judgment [i.e., both Jews and Gentiles].

Galatians 2:19

For it was by means of [this system of] law-keeping that I [realized I] was dead. This was so I could find life through a relationship with God.

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."

Treasury of Scripture Knowledge

Summary

(For they could not endure that which was commanded, And if so much as a beast touch the mountain, it shall be stoned, or thrust through with a dart:

Bible References

For they

Romans 3:19
Now we [all] know that everything the law says applies to those who are under [obligation to obey] that law, [Note: Here "the law" appears to refer to the Old Testament Scriptures generally, since Psalms and Isaiah are quoted. See verses 10-18]. This is so that the mouth of every objector may be stopped [i.e., from making excuses for his sin], and thereby bring the entire world under God's judgment [i.e., both Jews and Gentiles].
Galatians 2:19
For it was by means of [this system of] law-keeping that I [realized I] was dead. This was so I could find life through a relationship with God.
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."