Unpersuadable

I wish, for both our sakes, my dear unpersuadable girl, that the decision of this point lay with me. But why, when you know it does not, why should you thus perplex and urge me?

Source: wiktionary

He was unreasonable and unpersuadable and used intemperate language.

Source: wiktionary

For not by prayer to Zeus is access won; An unpersuadable heart hath Cronos' son.

Source: wiktionary

He did not boast, but it naturally betrayed itself, that he had persuaded his aunt where his uncle could do nothing, and on her laughing and noticing it, he owned that he believed (excepting one or two points) he could with time persuade her to any thing. […] The unpersuadable point, which he did not mention, Emma guessed to be good behaviour to his father.

Source: wiktionary