Though suspicion was very far from Miss Bennet’s general habits, she was absolutely incredulous here.
Elizabeth looked at her sister with incredulous solicitude, but said nothing.
With many compliments to them, and much self-gratulation on the prospect of a connection between the houses, he unfolded the matter—to an audience not merely wondering, but incredulous; for Mrs. Bennet, with more perseverance than politeness, protested he must be entirely mistaken; and Lydia, always unguarded and often uncivil, boisterously exclaimed: "Good Lord!
There are no more uses of "incredulous" in the book.
Show samples from other sources
I find it incredulous that you believe she is sincere.