Apastambadharmasutra 1.7

He shall not fulfil his sacred duties merely in order to acquire these worldly objects (as fame, gain, and honour).

For when they ought to bring rewards, (duties thus fulfilled) become fruitless.

(Worldly benefits) are produced as accessories (to the fulfilment of the law), just as in the case of a mango tree, which is planted in order to obtain fruit, shade and fragrance (are accessory advantages).

But if (worldly advantages) are not produced, (then at least) the sacred duties have been fulfilled.

Let him not become irritated at, nor be deceived by the speeches of hypocrites, of rogues, of infidels, and of fools.

For Virtue and Sin do not go about and say, 'Here we are;' nor do gods, Gandharvas, or Manes say (to men), 'This is virtue, that is sin.'

But that is virtue, the practice of which wise men of the three twice-born castes praise; what they blame, is sin.

He shall regulate his course of action according to the conduct which in all countries is unanimously approved by men of the three twice-born castes, who have been properly obedient (to their teachers), who are aged, of subdued senses, neither given to avarice, nor hypocrites.

Acting thus he will gain both worlds.

Trade is not lawful for a Brâhmana.

In times of distress he may trade in lawful merchandise, avoiding the following (kinds), that are forbidden:

(Particularly) men, condiments and liquids, colours, perfumes, food, skins, heifers, substances used for glueing (such as lac), water, young cornstalks, substances from which spirituous liquor may be extracted, red and black pepper, corn, flesh, arms, and the hope of rewards for meritorious deeds.

Among (the various kinds of) grain he shall especially not sell sesamum or rice (except he have grown them himself).

The exchange of the one of these (abovementioned goods) for the other is likewise unlawful.

But food (may be exchanged) for food, and slaves for slaves, and condiments for condiments, and perfumes for perfumes, and learning for learning.

Let him traffic with lawful merchandise which he has not bought,

With Muñga-grass, Balbaga-grass (and articles made of them), roots, and fruits,

And with (other kinds of) grass and wood which have not been worked up (into objects of use).

He shall not be too eager (after such a livelihood).

If he obtains (another lawful) livelihood, he shall leave off (trading).

Intercourse with fallen men is not ordained,

Nor with Apapâtras.

Now (follows the enumeration of) the actions which cause loss of caste (Patanîya).

(These are) stealing (gold), crimes whereby one becomes an Abhisasta, homicide, neglect of the Vedas, causing abortion, incestuous connection with relations born from the same womb as one's mother or father, and with the offspring of such persons, drinking spirituous liquor, and intercourse with persons the intercourse with whom is forbidden.

That man falls who has connection with a female friend of a female Guru, or with a female friend of a male Guru, or with any married woman.

Some (teachers declare), that he does not fall by having connection with any other married female except his teacher's wife.

Constant commission of (other) sins (besides those enumerated above) also causes a man to lose his caste.

Now follows (the enumeration of) the acts which make men impure (Asukikara).

(These are) the cohabitation of Aryan women with Sûdras,

Eating the flesh of forbidden (creatures),

As of a dog, a man, village cocks or pigs, carnivorous animals,

Eating the excrements of men,

Eating what is left by a Sûdra, the cohabitation of Aryans with Apapâtra women.

Some declare, that these acts also cause a man to lose his caste.

Other acts besides those (enumerated) are causes of impurity.

He who learns (that a man has) committed a sin, shall not be the first to make it known to others; but he shall avoid the (sinner), when performing religious ceremonies.