Apastambadharmasutra 2.1.2

Or they shall remove the stains with earth or water, sip water, and sprinkle the body with water.

Men of all castes, if they fulfil their (assigned) duties, enjoy (in heaven) the highest, imperishable bliss.

Afterwards when (a man who has fulfilled his duties) returns to this world, he obtains, by virtue of a remainder of merit, birth in a distinguished family, beauty of form, beauty of complexion, strength, aptitude for learning, wisdom, wealth, and the gift of fulfilling the laws of his (caste and order). Therefore in both worlds he dwells in happiness, (rolling) like a wheel (from the one to the other).

As the seed of herbs (and) trees, (sown) in good and well-cultivated soil, gives manifold returns of fruit (even so it is with men who have received the various sacraments).

The increase of the results of sins has been explained hereby.

Thus after having undergone a long punishment in the next world, a person who has stolen (the gold of a Brâhmana) or killed a (Brâhmana) is born again, in case he was a Brâhmana as a Kândâla, in case he was a Kshatriya as a Paulkasa, in case he was a Vaisya as a Vaina.

In the same manner other (sinners) who have become outcasts in consequence of their sinful actions are born again, on account of (these) sins, losing their caste, in the wombs (of various animals).

As it is sinful to touch a Kândâla, (so it is also sinful) to speak to him or to look at him. The penance for these (offences will be declared).

(The penance) for touching him is to bathe, submerging the whole body; for speaking to him to speak to a Brâhmana; for looking at him to look at the lights (of heaven).