One has to learn tolerance in the face of dualities such as happiness and distress, or cold and warmth, and by tolerating such dualities become free from anxieties regarding gain and loss.
Bhagavad Gita 2.45,
A spiritual master who is one hundred percent Krishna conscious is the bona ﬁde spiritual master.
Bhagavad Gita 2.8,
Bhagavad-gita is the instruction given by Krishna, and Srimad-Bhagavatam is the book containing topics exclusively about Krishna and His devotees. These two books are the special nectar of the words of Krishna.
Srimad Bhagavatam 4.4.44,
To show them special mercy, I, dwelling in their hearts, destroy with the shining lamp of knowledge the darkness born of ignorance.
Bhagavad Gita 10.11,
Among all kinds of killers, time is the ultimate because time kills everything.
Bhagavad Gita 10.33,
Intelligence refers to the power to analyze things in their proper perspective, and knowledge refers to understanding what is spirit and what is matter.
Bhagavad Gita 10.4,