Kautilya's Arthashastra 3.18.7

3.18.7

prakṛtyupavāde brāhmaṇakṣatriyavaiśyaśūdrāntāvasāyinām apareṇa pūrvasya tripaṇottarā daṇḍāḥ, pūrveṇāparasya dvipaṇādharāḥ, kubrāhmaṇādibhiś ca kutsāyām //

If among Bráhmans, Kshatriyas, Vaisyas, Súdras, and outcastes (antávasáyins), any one of a lower caste abuses the habits of one of a higher caste, the fines imposed shall increase from 3 panas upwards (commencing from the lowest caste). If any one of a higher caste abuses one of a lower caste, fines imposed shall decrease from 2 panas.

Contemptuous expressions such as 'a bad Bráhman' shall also be punished as above.