Exodus 19:13

There shall not an hand touch it, but he shall surely be stoned, or shot through; whether it be beast or man, it shall not live: when the trumpet soundeth long, they shall come up to the mount.

Cross-reference

Exodus 19:16 describes the actual trumpet blast and theophany, fulfilling the signal mentioned in v.13.

Exodus 19:19 continues the trumpet sound, directly connected to the signal in v.13.

Exodus 19:21 reiterates the warning about approaching the mountain, echoing the prohibition in v.13.

Genesis 3:3 has Eve adding 'neither shall you touch it, lest you die' — the same 'touch and die' prohibition found here.

Hebrews 12:20 directly quotes this command about stoning, using it to show the terror of the old covenant.