When we recite this mantra, we say “I take refuge in the supremely sacred vibhuti of the Lord, the wonderful vibhuti which bestows liberation, the sacred state which I desire to attain.”
Since this mantra is so powerful, we should recite it with respect and with sincerity in order that we gain the full benefit from it.
Vibhuti is a reminder that ash is the end product of all matter. Vibhuti has also an aspect of immortality, which makes it a fit offering for worshipping God. Only the Vibhuti remains unchanged, since it is the final result of the annihilation of the five elements of creation. It is symbolic of the ultimate reality that remains when our ego is burnt away by the fire of illumination.
"The Vibhuti that you smear on your forehead is intended to convey the basic spiritual lesson that everything will be reduced to ashes, including the brow that wears it".