Bhagavad Gita Verse 5.20

जो पुरुष प्रियको प्राप्त होकर हर्षित नहीं हो और अप्रियको प्राप्त होकर उद्विग्न न हो, वह स्थिरबुद्धि, संशयरहित, ब्रह्मवेत्ता पुरुष सच्चिदानन्दघन परब्रह्म परमात्मामें एकीभावसे नित्य स्थित है|

One truly becomes established in God when neither good circumstances make him happy, no bad Circumstance make him miserable. When a person reaches this type of balance in intellect and emotion, without a single doubt, with true knowledge of God, becomes eternally fixed in Him.