I would order my cause before him - Compare the notes at Isaiah 43:26. That is, I would arrange my arguments, or plead my cause, as one does in a court of justice. I would suggest the considerations which would show that I am not guilty in the sense charged by my friends, and that notwithstanding my calamities, I am the real friend of God.
And fill my mouth with arguments - Probably he means that he would appeal to the evidence furnished by a life of benevolence and justice, that he was not a hypocrite or a man of distinguished wickedness, as his friends maintained.