When: Presumably before 606 CE.
What: Chinese text, of the Chan (禅, Zen) school.
Title: Xin Xin Ming (信心銘, sometimes Hsin Hsin Ming).
Who: Attributed to Jianzhi Sengcan (僧璨) (died 606 CE), the "Third Chinese Patriarch of Chan after Bodhidharma and thirtieth Patriarch after Siddhartha Gautama Buddha."
Thanks to Python and CEDICT (link), I have magically equipped nearly every Chinese character in the Xin Xin Ming with (modern!) pronunciations and definitions. Mouse-over one to see a list of [pinyin] /meaning/.../ entries from the dictionary.
The translation is one I selected from a number I've come across over the years. I obtained permission from the translator, Richard B. Clarke, Founder and Zen Teacher of the Living Dharma Center, to reproduce his translation here.
Verses On the Faith Mind
Translated by Richard B. Clarke
The Great Way is not difficult
for those who have no preferences.
When love and hate are both absent
everything becomes clear and undisguised.
Make the smallest distinction, however
and heaven and earth are set infinitely apart.
If you wish to see the truth
then hold no opinions for or against anything.
To set up what you like against what you dislike
is the disease of the mind.
When the deep meaning of things is not understood
the mind's essential peace is disturbed to no avail.
The Way is perfect like vast space
where nothing is lacking and nothing is in excess.
Indeed, it is due to our choosing to accept or reject
that we do not see the true nature of things.
Live neither in the entanglements of outer things,
nor in inner feelings of emptiness.
Be serene in the oneness of things
and such erroneous views will disappear by themselves.
When you try to stop activity to achieve passivity
your very effort fills you with activity.
As long as you remain in one extreme or the other
you will never know Oneness.
Those who do not live in the single Way
fail in both activity and passivity,
assertion and denial. To deny the reality of things
to assert the emptiness of things is to miss their reality.
The more you talk and think about it,
the further astray you wander from the truth.
Stop talking and thinking,
and there is nothing you will not be able to know.
To return to the root is to find the meaning,
but to pursue appearances is to miss the source.
At the moment of inner enlightenment
there is a going beyond appearance and emptiness.
The changes that appear to occur in the empty world
we call real only because of our ignorance.
Do not search for the truth;
only cease to cherish opinions.
Do not remain in the dualistic state
avoid such pursuits carefully.
If there is even a trace of this and that, of right and wrong,
the Mind-essence will be lost in confusion.
Although all dualities come from the One,
do not be attached even to this One.
When the mind exists undisturbed in the Way,
nothing in the world can offend,
and when a thing can no longer offend, it ceases to exist in the old way.
When no discriminating thoughts arise, the old mind ceases to exist.
When thought objects vanish, the thinking-subject vanishes,
as when the mind vanishes, objects vanish.
Things are objects because of the subject (mind);
the mind (subject) is such because of things (object).
Understand the relativity of these two
and the basic reality: the unity of emptiness.
In this Emptiness the two are indistinguishable
and each contains in itself the whole world.
If you do not discriminate between coarse and fine
you will not be tempted to prejudice and opinion.
To live in the Great Way
is neither easy nor difficult,
but those with limited views
and fearful and irresolute: the faster they hurry, the slower they go,
and clinging (attachment) cannot be limited;
even to be attached to the idea of enlightenment is to go astray.
Just let things be in their own way
and there will be neither coming nor going.
continue on to the conclusion of the Xin Xin Ming (only because it wouldn't fit in one node)