text: As a supreme deity by the Upanishads, he's Rudra. The fourth meaning he gives is, रुत् शब्दात्मिका वाणी तत्प्रतिपाद्या आत्मविद्या वा ताम उपासकेभ्यो राति ददातीति रुद्रः. रुत् means the the divine speech, शब्दात्मिका वाणी.