בּ֣וֹא בַצּ֔וּר וְהִטָּמֵ֖ן בֶּֽעָפָ֑ר מִפְּנֵי֙ פַּ֣חַד יְהוָ֔ה וּמֵהֲדַ֖ר גְּאֹנֽוֹ׃
Enter into the rock, And hide thee in the dust, From before the terror of the LORD, And from the glory of His majesty.
Rashi on Isaiah
Come into the rock To come into the rock to escape in the cracks of the rocks.
Ibn Ezra on Isaiah
בא Infinitive: ‘ to enter ’ (comp. Hab. 2:3); or imperative : enter ; the advice which they will give each other.