Taittirīyopaniṣat 02.08 and 09
तस्माद्वा एतस्मात् प्राणमयात्। अन्योऽन्तर आत्मा मनोमयः। तेनैष पूर्णः। स वा एष पुरुषविध एव। तस्य पुरुषविधताम्। अन्वयं पुरुषविधः। तस्य यजुरेव शिरः । ऋग् दक्षिणः पक्षः। सामोत्तरः पक्षः । आदेश आत्मा। अथर्वाङ्गिरसः पुच्छं प्रतिष्ठा ॥८॥
Therefore, beyond this Prāṇamaya sheath, there is another inner essence, the Manomaya (mind-made). By that, this is complete. He is verily in the form of a person. Of him, the person-form is described. In continuity, the person-form of him, the Yajur is the head; the Ṛg is the right wing; the Sāma is the left wing; injunction is the Ātmān; and the Atharvāṅgiras is the tail, the foundation.
तदष्येश श्लोको भवति। यतो वाचो निवर्तन्ते। अप्राप्य मनसा सह। आनन्दं ब्रह्मणो विद्वान्। न बिभेति कदाचनेति। तस्यैष एव शारीर आत्मा । यः पूर्वस्य ॥९॥
Here is a verse about this: "From which words turn back, not attaining the bliss of Brahman together with the mind; but the knower of the bliss of Brahman does not fear at any time. Of him, this indeed is the embodied Ātmān, who is of the previous (one)."
Taittirīya Bhāshya 02.08 and 09
The Ātmān, the essence, the injunction (ādeśaḥ) - of the mind-made, Manomaya, is found by acceptance of the Ṛk recitation and the reconciliation of the defect by the Sāma. It is inaccessible to mind and speech. Having realized it, one realizes the nature of bliss.
... तस्मिन् सङ्कर्षणः स्थितः। शिरस्तस्य यजुर्नाम यज्ञानां हरणात् स्मृतम्॥
... in that Saṅkarṣaṇa is situated. His head is known as Yajur, as he takes away the rememberance from the sacrifices.
यजुःसंस्थं च बाहू तु ऋक्सामान्तःस्थितौ सदा। ऋगर्चनायाः स्वीकारात् साम दोषात् समीकृतेः॥
Placed in the Yajurveda, and the arms always situated at the end of Ṛk and Sāma, by the acceptance of the Ṛk recitation and the reconciliation of the defect by the Sāma.
पञ्चरात्रगतं मध्यमादेशाख्यं सुविस्तृतेः। अथर्वाख्यं तथा पुच्छमधरं चाङ्गिनां रसः। मनोवाचामगम्यं तं ज्ञात्वाऽऽनन्दस्वरूपिणम् ॥
Having known that essence, which is described as the middle instruction in the Pañcarātra, as Atharva, the lower tail, and the essence of the limbs, which is inaccessible to mind and speech, one realizes the nature of bliss.
कुतश्चिन्न बिभेत्येव ...
He does not fear anything at all ...
