Trường Bộ Kinh (Digha Nikaya) 1:618
SUJATOEvameva ajjhattaṁ arūpasaññī eko bahiddhā rūpāni passati pītāni pītavaṇṇāni pītanidassanāni pītanibhāsāni.
In the same way, not perceiving form internally, someone sees forms externally that are yellow, with yellow color and yellow appearance.