CHĀNDOGYA UPANISHAD · 2.24.3
पुरा प्रातरनुवाकस्योपाकरणाज् जघनेन गार्हपत्यस्योदाङ्मुख उपविश्य स वासवं सामाभिगायति ॥
purā prātaranuvākasyopākaraṇāj jaghanena gārhapatyasyodāṅmukha upaviśya sa vāsavaṃ sāmābhigāyati ॥
Before the beginning of the Prâtaranuvâka, (matin-chant), the sacrificer, sitting down behind the household altar (gârhapatya), and looking towards the north, sings the Sâman, addressed to the Vasus:
F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)