Verse 7.26.2

तदेष श्लोको न पश्यो मृत्युं पश्यति न रोगं नोत दुःखतां सर्वं ह पश्यः पश्यति सर्वमाप्नोति सर्वश इति स एकधा भवति त्रिधा भवति पञ्चधा सप्तधा नवधा चैव पुनश्चैकादशः स्मृतः शतं च दश चैकश्च सहस्राणि च विंशतिराहारशुद्धौ सत्त्वशुद्धौ ध्रुवा स्मृतिः स्मृतिलम्भे सर्वग्रन्थीनां विप्रमोक्षस्तस्मै मृदितकषायाय तमसस्पारं दर्शयति भगवान्सनत्कुमारस्तं स्कन्द इत्याचक्षते तं स्कन्द इत्याचक्षते ॥ ७.२६.२ ॥
॥ इति षड्विंशः खण्डः ॥
॥ इति सप्तमोऽध्यायः ॥

tadeṣa śloko na paśyo mṛtyuṃ paśyati na rogaṃ nota duḥkhatāṃ sarvaṃ ha paśyaḥ paśyati sarvamāpnoti sarvaśa iti sa ekadhā bhavati tridhā bhavati pañcadhā saptadhā navadhā caiva punaścaikādaśaḥ smṛtaḥ śataṃ ca daśa caikaśca sahasrāṇi ca viṃśatirāhāraśuddhau sattvaśuddhau dhruvā smṛtiḥ smṛtilambhe sarvagranthīnāṃ vipramokṣastasmai mṛditakaṣāyāya tamasaspāraṃ darśayati bhagavānsanatkumārastaṃ skanda ityācakṣate taṃ skanda ityācakṣate || 7.26.2 ||
|| iti ṣaḍviṃśaḥ khaṇḍaḥ ||
|| iti saptamo'dhyāyaḥ ||

2. Here is a verse on the subject: ‘He who has realized the Self does not see death. For him there is no disease or sorrow. Such a seer sees everything [as it is] and also attains everything in whatever way [he wants].’ He is one [i.e., before creation; but after creation], he is in three forms, five forms, seven forms, and nine forms. Then again, he is in eleven, a hundred and ten, and even a thousand and twenty forms. If one eats pure food, one’s mind becomes pure. If the mind is pure, one’s memory becomes strong and steady. If the memory is good, one becomes free from all bondages. The revered Sanatkumāra freed Nārada from all his shortcomings and led him beyond darkness [i.e., ignorance]. The wise say that Sanatkumāra is a man of perfect knowledge.

Word-for-word explanation:

Tat eṣaḥ ślokaḥ, here is a verse on the subject; paśyaḥ, a person who sees thus [i.e., who knows the Self]; mṛtyum na paśyati, does not see death; na rogam, nor disease; na uta duḥkhatam, nor suffering; paśyaḥ, a person who sees thus; sarvam ha paśyati, sees everything; sarvam āpnoti, he obtains all; sarvaśaḥ, in every way. Saḥ ekadhā bhavati, he is one [before the creation]; tridhā bhavati, [and] he is in three forms [fire, water, and earth]; pañcadhā, in five forms; saptadhā, in seven forms; ca eva navadhā, and in nine forms; punaḥ ca, also; ekādaśaḥ smṛtaḥ, he is thought of as having eleven forms; śatam ca daśa ca, and one hundred and ten forms; ekaḥ ca sahasrāṇi ca viṃśatiḥ, and also one thousand and twenty forms; āhāra-śuddhau, if the food is pure; sattva-śuddhiḥ, the mind is pure; sattva-śuddhau, if the mind is pure; dhruvā smṛtiḥ, the memory is strong and steady; smṛtilambhe, when the memory is good; sarva-granthīnām, from all bondages; vipramokṣaḥ, one is freed; tasmai, to him [to Nārada]; mṛditakaṣāyāya, who was free from all impurities; bhagavān sanatkumāraḥ, revered Sanatkumāra; tamasaḥ pāram, beyond darkness; darśayati, showed; tam, him [Sanatkumāra]; skanda iti ācakṣate, they refer to as ‘Skanda’ [the wise]; tam, him [Sanatkumāra]; skanda iti ācakṣate, they refer to as ‘Skanda’ [the wise]. Iti ṣaḍviṃśaḥ khaṇḍaḥ, here ends the twenty-sixth section. Iti chāndogyopaniṣadi saptamaḥ adhyāyaḥ, here ends the seventh chapter of the Chāndogya Upaniṣad.

Commentary:

But how do you attain this knowledge? You have to have pure food. Pure food makes the body and mind pure, and you are then able to keep the mind under control. By controlling the mind, you are able to go beyond ignorance and become free from bondage. Like Sanatkumāra, you earn the title ‘Skanda,’ the wise one.