to say no
I should have said no.
Il n'a pas osé dire non à mon plan.
He didn't dare say no to my plan.
Il ne sait pas dire non aux femmes.
He doesn't know how to say no to women.
— Femmes au bord de la crise de nerfs (1988)
Je ne l'ai jamais entendu dire non.
I've never heard him say no.