Hebrews 12:18

12:18 For you have not come to something that can be touched, ¹  to a burning fire and darkness and gloom and a whirlwind

Hebrews 12:25

12:25 Take care not to refuse the one who is speaking! For if they did not escape when they refused the one who warned them on earth, how much less shall we, if we reject the one who warns from heaven?

[12:18]  ¹ tn This describes the nation of Israel approaching God on Mt. Sinai (Exod 19). There is a clear contrast with the reference to Mount Zion in v. 22, so this could be translated “a mountain that can be touched.” But the word “mountain” does not occur here and the more vague description seems to be deliberate.