Bhagwad Gita
Chapter 6, Verse 32
आत्मौपम्येन सर्वत्र समं पश्यति योऽर्जुन।
सुखं वा यदि वा दुःखं सः योगी परमो मतः।।6.32।।
He is a perfect yogi who, by comparison to his own self, sees the true equality of all beings, both in their happiness and distress, O Arjuna!