The fourth chapter of the Bhagavad Gita is Jnana Karma Sanyasa Yoga. In this chapter, Krishna glorifies the Karma Yoga and imparts the Transcendental Knowledge (the knowledge of the soul and the Ultimate Truth) to Arjuna. He reveals the reason behind his appearance in this material world. He reveals that even though he is eternal, he reincarnates time after time to re-establish dharma and peace on this Earth. His births and activities are eternal and are never contaminated by material flaws. Those persons who know and understand this Truth engage in his devotion with full faith and eventually attain Him. They do not have to take birth in this world again.
Other yogis undertake sacrifice to gods alone, Others offer the Self, as a sacrifice by the Self itself, in the fire of Brahman.OPEN VERSE
Others offer the organs, viz ear etc., in the fires of self-control. Others offer the objects, viz sound etc., in the fires of the organs.OPEN VERSE
Others offer all the activities of the organs and the activities of the vital force into the fire of the yoga of self-control which has been lighted by Knowledge.OPEN VERSE
Similarly, others are performers of sacrifices through wealth, through austerity, through yoga, and through study and knowledge; others are ascetics with severe vows.OPEN VERSE
Constantly practising control of the vital forces by stopping the movements of the outgoing and the incoming breaths, some offer as a sacrifice the outgoing breath in the incoming breath; while still others, the incoming breath in the outgoing breath. Others, having their food regulated, offer the vital forces in the vital forces. All of them are knowers of the sacrifice and have their sins destroyed by sacrifice.OPEN VERSE
Those who partake of the nectar left over after a sacrifice, reach the eternal Brahman. This world ceases to exist for one who does not perform sacrifices. What to speak of the other (world), O best among the Kurus (Arjuna)!OPEN VERSE