The liaison is optional after *non* and rarely done.

Here is then its mainstream pronunciation :

> *La philosophie consiste à dire et non à faire.* /nɔ̃.a.fɛʁ/

In careful formal speech, the liaison might be done and the rule is then to drop the nasalisation:

> *La philosophie consiste à dire et non à faire.* /nɔ.na.fɛʁ/

There are however a few cases where the liaison is always done<sup>1</sup> and the nasalisation sometimes preserved, the idioms *[nul et non avenu][1]* and *[non-événement][2]* (Thanks to @Personne for the example).

As a standalone phrase, *non à faire* is slightly odd. We'd rather say *Pas à faire* where the lack liaison is also becoming the standard.

Finally, liaisons is a hot topic. Usage evolves with time and might also vary depending on the region or the social category of speakers so liaisons might move from mandatory to optional, from optional to forbidden and reciprocally, and among the optional liaisons, opinions might differ.

<sup>1</sup><sub>Surprisingly, the LBU states the liaison shouldn't be done in *non avenu*, but I have never heard it pronounced that way.</sub>


  [1]: https://fr.wiktionary.org/wiki/nul_et_non_avenu#fr
  [2]: https://fr.wiktionary.org/wiki/non-%C3%A9v%C3%A9nement