Chandogya Upanishad 2.10

atha khalv ātmasaṃmitam atimṛtyu saptavidhaṃ sāmopāsīta hiṅkāra iti tryakṣaram prastāva iti tryakṣaram tat samam

Next let a man meditate on the sevenfold Sâman which is uniform in itself and leads beyond death. The word hinkâra has three syllables, the word prastâva has three syllables: that is equal (sama).

ādir iti dvyakṣaram pratihāra iti caturakṣaram tata ihaikam tat samam

The word âdi (first, Om) has two syllables, the word pratihâra has four syllables. Taking one syllable from that over, that is equal (sama).

udgītha iti tryakṣaram upadrava iti caturakṣaraṃ tribhis tribhiḥ samaṃ bhavati akṣaram atiśiṣyate tryakṣaram tat samam

The word udgîtha has three syllables, the word upadrava has four syllables. With three and three syllables it should be equal. One syllable being left over, it becomes trisyllabic. Hence it is equal.

nidhanam iti tryakṣaram tat samam eva bhavati tāni ha vā etāni dvāviṃśatir akṣarāṇi

The word nidhana has three syllables, therefore it is equal. These make twenty-two syllables.

ekaviṃśatyādityam āpnoti ekaviṃśo vā ito 'sāv ādityaḥ dvāviṃśena param ādityāj jayati tan nākam tad viśokam

With twenty-one syllables a man reaches the sun (and death), for the sun is the twenty-first from here; with the twenty-second he conquers what is beyond the sun: that is blessedness, that is freedom from grief.

āpnotīhādityasya jayam paro hāsyādityajayāj jayo bhavati ya etad evaṃ vidvān ātmasaṃmitam atimṛtyu saptavidhaṃ sāmopāste sāmopāste

He obtains here the victory over the sun (death), and there is a higher victory than the victory over the sun for him, who knowing this meditates on the sevenfold Sâman as uniform in itself, which leads beyond death, yea, which leads beyond death.