Chapter 18 · verse 38 · gita.yoga.org

Bhagavad Gita 18.38

विषयेन्द्रियसंयोगाद्यत्तदग्रेऽमृतोपमम्।परिणामे विषमिव तत्सुखं राजसं स्मृतम्

That happiness which arises from the contact of the senses with the objects, which is initially like nectar but eventually like poison, is said to be Rajasic.