Kautilya's Arthashastra 3.13.3

3.13.3

mlecchānām adoṣaḥ prajāṃ vikretum ādhātuṃ vā //

THE selling or mortgaging by kinsmen of the life of a Súdra who is not a born slave, and has not attained majority, but is an Arya in birth shall be punished with a fine of 12 panas; of a Vaisya, 24 panas; of a Kshatriya, 36 panas; and of a Bráhman, 48 panas. If persons other than kinsmen do the same, they shall be liable to the three amercements and capital punishment respectively: purchasers and abettors shall likewise be punished. It is no crime for Mlechchhas to sell or mortgage the life of their own offspring. But never shall an Arya be subjected to slavery.