Neither by action nor by progeny nor by wealth but by renunciation alone one attains immortality (or Self-knowledge).

Right is austerity. Truth is austerity. Understanding of the scriptures is austerity. Subduing of one’s senses is austerity. Restraint of the body through such means like fast is austerity. Cultivation of a peaceable disposition is austerity. Giving gifts without selfish motives is austerity. Worship is austerity.
Mahanarayana Upanishad
Mahanarayana Upanishad