for whose cause, &c.. for what cause. The lot had told them the person, but not the "cause". So they appeal to Jonah.
Related Commentaries of Jonah 1:8
Jonah 1:8
8 Then said they unto him, Tell us, we pray thee, for whose cause this evil is upon us; What is thine occupation? and whence comest thou? what is thy country? and of what people art thou?