Trường Bộ Kinh (Digha Nikaya) 1:621
SUJATOAjjhattaṁ arūpasaññī eko bahiddhā rūpāni passati lohitakāni lohitakavaṇṇāni lohitakanidassanāni lohitakanibhāsāni.
Not perceiving form internally, someone sees forms externally that are red, with red color and red appearance.