CC Madhya 25.48

‘bhagavattā’ mānile ‘advaita’ nā yāya sthāpana
ataeva saba śāstra karaye khaṇḍana
Synonyms: 
bhagavattā — the Personality of Godhead; mānile — if one accepts; advaita — monism or nondualism; — not; yāya — is possible; sthāpana — establishing; ataeva — therefore; saba — all; śāstra — revealed scriptures; karaye — does; khaṇḍana — refutation.
Translation: 
“If one accepts the Personality of Godhead, the philosophy that maintains that God and the living entity are one cannot be established. Therefore Śaṅkarācārya argued against and refuted all kinds of revealed scriptures.