Bhagavad Gita · 10.33

अक्षराणामकारोऽस्मि द्वन्द्वः सामासिकस्य च।अहमेवाक्षयः कालो धाताहं विश्वतोमुखः॥

akṣharāṇām a-kāro 'smi dvandvaḥ sāmāsikasya cha aham evākṣhayaḥ kālo dhātāhaṁ viśhvato-mukhaḥ

Among letters, I am the letter A. Among compound words, I am the dual compound. I alone am imperishable time. I am the creator facing all directions.

— Bhagavad Gita 10.33

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)