The saying is attributed to Ahmed Ibn Abu al-Hassan al-Nuri.
No, I'm not a scholar of Sufism. I came across the quote in Kim Stanley Robinson's Mars trilogy years ago, and it spoke to me in a certain way -- not as a moral or religious principle per se so much as a practical strategy for avoiding undesired entanglements, particularly vis a vis the state.
The jury's still out on how well that works, by the way.
Anyway, I thought I'd throw it out there for discussion.