Śatapatha Brāhmaṇa ("of a hundred paths") 4.1.3.9

4.1.3.9

no eva niṣṭhīvet | tasmādyadyapyāsakta iva manyetābhivātam parīyācrīrvai somaḥ pāpmā yakṣmaḥ sa yathā śreyasyāyati pāpīyānpratyavarohedevaṃ hāsmādyakṣmaḥ pratyavarohati

Nor must one spit thereat; even though he should think himself ever so much affected, let him go round it windward; for Soma means eminence, and disease meanness: even as at the approach of his superior the meaner man would get down (from his seat), so does disease go down before him (Soma).