Bhagavad Gita Verse 17.12

परन्तु हे अर्जुन ! केवल दम्भाचरण के लिये अथवा फल को भी दृष्टि में रखकर जो यज्ञ किया जाता है, उस यज्ञ को तू राजस जान|

However, O Bharata, a sacrifice that is done purely with the intention of receiving some reward, or done for the sake of display, is known as a Rajas sacrifice, which is an impure sacrifice.