The mahamrutyunjaya mantra

The mahamrutyunjaya mantra is

ॐ त्र्यम्बकं यजामहे सुगन्धिं पुष्टिवर्धनं

उर्वारुकमिव बन्धनात् मृत्योर मुक्षीय मामृतात्..

om tryambakam yajaamahe sugandhim pushtivardhanam

urvaarukamiva bandhanaat mrutyormuksheeya maamrutaat

This is found in Rg Veda 7-59-12, Yajur veda Vajasaneyi Samhita 3-60 and atharvaveda 14-1-70

We worship and offer oblations to Rudra the thrayambaka( three eyed) He spreads frangrance and enhances our nourishment.

May He be pleased to realease me like the ripe cucumber from its stem, from mortal life but not from immortality

The cucumber falls down from its tendrils when it is ripe, but it has already the seeds of immortality within it.. And the separation from the mother tendril comes only when the fruit is ripe.. This would imply that by the Grace of Lord Mrutyunjaya Rudra,death may visit us with peace at ripe old age and also enable us to reach immortality at His lotus feet

In fact the mantra is found in Yajurveda Vajasaneeyi Samhita in a slightly modified form..

this is a prayer by a newly wedded lady for the benefit and longevity of her husband

ॐ त्र्यम्बकं यजामहे सुगन्धिं पतिवर्धनं

उर्वारुकमिव बन्धनात् मृत्योर मुक्षीय मामृतात् .

om tryambakam yajaamahe sugandhim pativardhanam

urvaarukamiva bandhanaat mrutyormuksheeya maamrutaat

Here the word Pathivardhanam… the enhancer of the longevity and welfare of the husband is used instead of the word Pustivardhanam..

  (yajurveda Vajasaneyi Samhita, 3-60)