Trường Bộ Kinh (Digha Nikaya) 1:616
SUJATOAjjhattaṁ arūpasaññī eko bahiddhā rūpāni passati pītāni pītavaṇṇāni pītanidassanāni pītanibhāsāni.
Not perceiving form internally, someone sees forms externally that are yellow, with yellow color and yellow appearance.