Bhagavad Gita · 2.57

यः सर्वत्रानभिस्नेहस्तत्तत्प्राप्य शुभाशुभम्।नाभिनन्दति न द्वेष्टि तस्य प्रज्ञा प्रतिष्ठिता॥

yaḥ sarvatrānabhisnehas tat tat prāpya śhubhāśhubham nābhinandati na dveṣhṭi tasya prajñā pratiṣhṭhitā

One who is unattached everywhere, who neither rejoices nor hates upon encountering good or evil — such a person's wisdom is firmly established.

— Bhagavad Gita 2.57

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)