Why did Nietzsche view morality as cowardice?

“What he meant by that was that, most of what people claim to be moral virtue, is merely their fear to do anything that they would actually like to do that society would deem inappropriate. Has nothing to do with morality whatsoever.”
— Jordan Peterson

Hence, the duller the eye, the more extensive the good

Suspicious.-- To admit a belief merely because it is a custom - but that means to be dishonest, cowardly, lazy! - And so could dishonesty, cowardice and laziness be the preconditions for morality?

from Nietzsche's Daybreak,s. 101, R.J. Hollingdale transl.