Yechezkel 3:5-7

Orthodox Jewish Bible

⁵ For thou art not sent to an Am Imkei Safah (a people of indecipherable language) and of obscure lashon, but to Bais Yisroel;

⁶ Not to amim rabbim of indecipherable language and obscure lashon whose words thou canst not understand. Surely, had I sent thee to them, they would have paid heed unto thee.

⁷ But Bais Yisroel will not pay heed unto thee; for they will not pay heed unto Me; for kol Bais Yisroel are khizkei metzach (hard-set of brow) and keshei-lev (hard-hearted).