Bhagavad gita, specifically Renunciation

The Supreme Lord said, To give up the results of all activities is called renunciation [tyaga] by the wise. And that state is called the renounced order of life [sannyasa] by great learned men.

Chapter 18, Verse 3.
Some learned men declare that all kinds of fruitive activities should be given up, but there are yet other sages who maintain that acts of sacrifice, charity and penance should never be abandoned.

Chapter 18, Verse 4.
O best of the Bharatas, hear from Me now about renunciation. O tiger among men, there are three kinds of renunciation declared in the scriptures.

Chapter 18, Verse 5.
Acts of sacrifice, charity and penance are not to be given up but should be performed. Indeed, sacrifice, charity and penance purify even the great souls.

Chapter 18, Verse 6.
All these activities should be performed without any expectation of result. They should be performed as a matter of duty, O son of Prtha. That is My final opinion.

Chapter 18, Verse 7.
Prescribed duties should never be renounced. If, by illusion, one gives up his prescribed duties, such renunciation is said to be in the mode of ignorance.

Chapter 18, Verse 8.
Anyone who gives up prescribed duties as troublesome, or out of fear, is said to be in the mode of passion. Such action never leads to the elevation of renunciation.

Chapter 18, Verse 9.
But he who performs his prescribed duty only because it ought to be done, and renounces all attachment to the fruit--his renunciation is of the nature of goodness, O Arjuna.

Chapter 18, Verse 10.
Those who are situated in the mode of goodness, who neither hate inauspicious work nor are attached to auspicious work, have no doubts about work.

Chapter 18, Verse 11.
It is indeed impossible for an embodied being to give up all activities. Therefore it is said that he who renounces the fruits of action is one who has truly renounced.

Chapter 18, Verse 12.
For one who is not renounced, the threefold fruits of action--desirable, undesirable and mixed--accrue after death. But those who are in the renounced order of life have no such results to suffer or enjoy.