Khadiragrihyasutra 4.2.6

4.2.6

gaure bhūmibhāge brāhmaṇo lohite kṣatriyaḥ kṛṣṇe vaiśyo 'vasānaṃ joṣayet samaṃ lomaśamaniriṇamaśuṣkam / 6

A Brâhmana should elect the site for building his house on white ground, a Kshatriya on red, a Vaisya on black, which should be even, covered with grass, not salinous, not dry—