en_tn/gen/26/23.md

Isaac went up from there to Beersheba

Here "went up" is probably a reference to going north. Say that he departed in the most natural way for your language. AT: "Isaac left there and went to Beersheba"

multiply your descendants

"will cause your descendants to increase greatly" or "will cause your descendants to be very many"

for my servant Abraham's sake

"for my servant Abraham" or you can make the full meaning explicit. AT: "because I promised my servant Abraham that I would do this" (See: rc://en/ta/man/translate/figs-explicit)

Isaac built an altar there

You can make explicit why Isaac built an altar. AT: "Isaac built an altar there to sacrifice to Yahweh" (See: rc://en/ta/man/translate/figs-explicit)

called on the name of Yahweh

To "call on" means to pray or to worship. Here "name" stands for Yahweh. AT: "prayed to Yahweh" or "worshiped Yahweh" (See: rc://en/ta/man/translate/figs-metonymy)