Yehudah ben Shmuel (Yehudah haChasid) of Regensburg (1140 -- 1217) wrote Sefer Chasidim (Book of the Pious).

Meditation from Sefer Chassidim

Be honourable in your business dealings. Do not say that such and such a price has been offered you for your wares, when the thing is not true; and do not act as though you had a desire to sell what you possessed, when there is in your mind no serious thought of doing so. Such things are unworthy of an Israelite.

On the worldly possessions of those who oppress the workman, or who buy stolen goods, rests no blessing. They or their children will lose all they have. Let no one be troubled in mind or take up wrong ideas because of the prosperity of wicked people, or of such as hold parents in little honour; their end is evil.

In your intercourse with non-Jews, be careful to be as wholly sincere as in that with Jews. In most places, Jews are not unlike Christians in their morals and usages.

If an assassin take refuge with you, give him no protection, even though he be Jewish. If one who bears a heavy burden on his shoulders meet you on a narrow and difficult path, make way for him, even though he be not Jewish.

To him who is merciful, God is merciful. The pitiless man is like the cattle of the field that are indifferent to the sufferings of their kind.

There are three sorts of people for whom we ought to feel especial sympathy: a reasonable, prudent creature subjected to a capricious fool; a good man who has to take orders from a base man; and a noble being dependent upon one of vulgar nature. There are three to whom we should sternly close our hearts: a cruel person who commits vile things; the fool who rushes into ruin in spite of warning; and the ingrate. Ingratitude is the blackest of faults; it is not to be shown even towards the dumb creatures that we use.