From the Kitab al-Isharat, III.7.25:
Admonition: Do not let it occur to you that happiness in the Hereafter is of a single kind. And do not let it occur to you that it is not attained at all except through perfection in knowledge, even though that makes that kind the noblest. And do not think that the various sins sever the bond of salvation. Rather, what subjects to eternal destruction is a type of ignorance and what exposes to finite punishment is type of vice and a certain degree of it, which happens to only a few individual people. Do not, then, listen to one who restricts salvation to a few number and denies it to the ignorant and sinful forever – God’s mercy is all-embracing [7:156 ]. You will hear this further explained [cf. Isharat, IV.8.11-3].