en_tn_condensed/isa/64/01.md

General Information:

The people of Israel continue speaking to Yahweh. (See: Isaiah 63:11)

Oh, if you had

Isaiah introduces this desire for Yahweh's presence in their past history with a strong exclamation. (See: rc://en/ta/man/translate/figs-hypo)

if you had split open the heavens

If Yahweh had shown himself very dramatically by tearing open the sky. The words "split open" refer to ripping a piece of cloth apart. (See: rc://en/ta/man/translate/figs-metaphor)

mountains would have shaken

The mountains would have trembled as in an earthquake. (See: rc://en/ta/man/translate/figs-hypo)