en_tn_lite_do_not_use/rom/10/16.md

not all of them obeyed

Here "they" refers to the Jews. "not all of the Jews obeyed"

Lord, who has believed what they have heard from us?

Paul is using this question, which Isaiah prophesied in the Scriptures, to emphasize that many Jews would not believe in Jesus. You can translate this as a statement. Alternate translation: "Lord, so many of them do not believe our message!" (See: rc://en/ta/man/translate/figs-rquestion)

what they have heard from us

Here, "us" refers to God and Isaiah.