Śatapatha Brāhmaṇa ("of a hundred paths") 13.8.3.11

13.8.3.11

tadvai na mahatkuryāt nenmahadagham karavāṇīti yāvānudbāhuḥ puruṣastāvatkṣatriyasya kuryānmukhadaghnam brāhmaṇasyopasthadaghnaṃ striyā ūrudaghnam vaiśyasyāṣṭhīvaddaghnaṃ śūdrasyaivamvīryā hyeta iti

Let him not make it (the sepulchral mound) too large, lest he make the (deceased's) sin large. For a Kshatriya he may make it as high as a man with upstretched arms, for a Brâhmana reaching up to the mouth, for a woman up to the hips, for a Vaisya up to the thighs, for a Sûdra up to the knee; for suchlike is their vigour.