BṚHADĀRAṆYAKA UPANISHAD · 4.4.9

तस्मिञ् शुक्लम् उत नीलम् आहुः पिङ्गलं हरितं लोहितं च ।
एष पन्था ब्रह्मणा हानुवित्तस् तेनैति ब्रह्मवित् पुण्यकृत् तैजसश् च ॥

tasmiñ śuklam uta nīlam āhuḥ piṅgalaṃ haritaṃ lohitaṃ ca ।
eṣa panthā brahmaṇā hānuvittas tenaiti brahmavit puṇyakṛt taijasaś ca ॥

'On that path they say that there is white, or blue, or yellow, or green, or red; that path was found by Brahman, and on it goes whoever knows Brahman, and who has done good, and obtained splendour.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)