Zen precept #12: "Not speaking of others' faults" -- witnessing but not dwelling on people's failings

Zen precept #12: Not speaking of other people's faults.
A straightforward but difficult precept to keep because the human ego is bent on separating ourselves from others, and what better way to do this than sewing seeds of disharmony and disrespect through our speech.

I like what the 13th century Zen master Dogen teaching on this precept:

Within the buddha dharma,
all are on the same path, the same dharma,
the same realization, the same practice.
So the faults of others will not be discussed,
and confusing speech will not occur.

--Dogen, Essay on Teaching and Conferring the Precepts