en_tn_condensed/isa/26/04.md

Yah, Yahweh

"Yah" is a shortened form of the name "Yahweh."

Yahweh, is an everlasting rock

Yahweh having the power to protect his people is spoken of as if he were a tall rock where people could go to escape from their enemies. (See: rc://en/ta/man/translate/figs-metaphor)