Sutra 29
tatah pratyakchetanadhigamo-apyantaraayabhaavashcha
tatah : from that (above detailed practice)
pratyakchetan : inner consciousness
adhigam : gyan/ awakening
antaraaya : obstacles
abhaav : lack
cha : and
Patanjali now details the effect of chanting and internalising the name of ishvar
From that (chanting and internalising of om), one gets the gyan of inner self and also gets riddance from obstacles on the path of yoga.
Mantra is codified energy in the form of sound. Om is the samavesh of all sounds and its jaap and internalisation has the power to remove all impurities, awakening the inner-consciousness and paving way to achieve the ultimate
