Yoga Sūtra Chapter One verse 27
तस्य वाचकः प्रणवः ॥२७॥
tasya vācakaḥ praṇavaḥ ||27||
Its expression is sacred.
tasya - itsvācaka - expression; verbal , expressed by words; speaking, saying, telling anythingpraṇava - sacred syllable; the syllable that gives life; the mystical name of the deity; the mystical or sacred syllable om; name of the trinityCommentaries and Reflections
Commentary by Paul Harvey:
Its syllables are sacred.