Skandapurana 16.28.47

16.28.47

ādeśaṃ paṭhate yastu saṃjighṛkṣuḥ pratigraham ..
tīrthe caiva viśeṣeṇa brahmaghnaḥ saiva netaraḥ ..
sthito vai nṛpaterdvāri na kuryādvedavikrayam .. 47 ..

He who recites a command wishing to seize an acceptance of gifts, / especially at a sacred ford, is indeed a killer of a brahmin and none other. / Standing at a king's gate, one must not sell the Veda.