KAṬHA UPANISHAD · 1.2.13

एतच्छ्रुत्वा सम्परिगृह्य मर्त्यः
प्रवृह्य धर्म्यमणुमेतमाप्य ।
स मोदते मोदनीयँ हि लब्ध्वा
विवृतँ सद्म नचिकेतसं मन्ये ॥ १३॥

etacchrutvā samparigṛhya martyaḥ
pravṛhya dharmyamaṇumetamāpya ।
sa modate modanīyam̐ hi labdhvā
vivṛtam̐ sadma naciketasaṃ manye ॥ 13॥

When mortal man has heard, when he has grasped, when he has forcefully separated the Righteous One from his body and won that subtle Being, then he has delight, for he has got that which one can indeed delight in. Verily I deem of Nachiketas as a house wide open.

Sri Aurobindo · CWSA 18, p. 111