"ओँ तत्सत्" मन्त्र माहात्म्यम्The greatness of the mantra oṁ tat sat
Verse 164
त्रिपदोऽयं महामन्त्रः सर्वकारणकारणम् । साधनादस्य मन्त्रस्य भवेन्मृत्युञ्जयः स्वयम् ॥ १६४ ॥
tripadō’yaṁ mahāmantraḥ sarvakāraṇakāraṇam | sādhanādasya mantrasya bhavēnmṛtyuñjayaḥ svayam || 164 ||
Translation
This great mantra of three words is the cause of all causes. By the practice of this mantra one becomes in himself the conqueror of death.
Word by word
- tri
- three
- padō
- (padaḥ) of words
- ayaṁ
- (ayam) this
- mahā
- great
- mantraḥ
- mantra
- sarva
- all
- kāraṇa
- the cause of causes
- sādhanād
- (sādhanāt) by the practice
- asya
- of this
- mantrasya
- mantra
- bhavēn
- (bhavet) one becomes
- mṛtyuñjayaḥ
- the conqueror of death
- svayam
- in himself
Meaning
The three words are oṁ, tat and sat. "Mṛtyuñjaya" is a name of Śiva, and the verse says that the practitioner himself comes to deserve it.

Commentary
Hariharānanda Bhāratī’s Sanskrit commentary, translated
See the commentary on verse 161.