CHĀNDOGYA UPANISHAD · 5.1.2
यो ह वै वसिष्ठं वेद वसिष्ठो ह स्वानां भवति ।
वाग् वाव वसिष्ठः ॥
yo ha vai vasiṣṭhaṃ veda vasiṣṭho ha svānāṃ bhavati ।
vāg vāva vasiṣṭhaḥ ॥
He who knows the richest, becomes himself the richest. Speech indeed is the richest.
F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)