KAIVALYA UPANISHAD · 11

आत्मानमरणिं कृत्वा प्रणवं चोत्तरारणिम् ।
ज्ञाननिर्मथनाभ्यासात्पापं दहति पण्डितः ॥ ११॥

ātmānamaraṇiṃ kṛtvā praṇavaṃ cottarāraṇim ।
jñānanirmathanābhyāsātpāpaṃ dahati paṇḍitaḥ ॥ 11॥

Having constituted his body an Arani (the lower attritional piece of wood) and Pranava (Om), the upper Arani, a wise man burns Ajñāna by the churning of meditation.

K. Narayanasvami Aiyar · Thirty Minor Upanishads (1914), pp. 31–33