Bhagavad Gita · 1.47

ॐ तत्सदिति श्रीमद्भगवद्गीतासूपनिषत्सु ब्रह्मविद्यायां योगशास्त्रेश्रीकृष्णार्जुनसंवादे अर्जुनविषादयोगो नाम प्रथमोऽध्यायः॥

oṁ tat sad iti śhrīmad bhagavad-gītāsūpaniṣhatsu brahma-vidyāyāṁ yoga-śhāstre śhrī-kṛṣhṇārjuna-saṁvāde arjuna-viṣhāda-yogo nāma prathamo 'dhyāyaḥ

Thus ends the first chapter of the Bhagavad Gita, entitled 'The Yoga of Arjuna's Dejection,' in the dialogue between Sri Krishna and Arjuna, which forms part of the Brahma Vidya (science of the Supreme) and Yoga Shastra (scripture of yoga) found in the Upanishads of the Shrimad Bhagavad Gita.

— Bhagavad Gita 1.47

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