Gita 5:27 to 28
Shutting out all external sense objects, keeping the eyes and vision concentrated between the two eyebrows, suspending the inward and outward breaths within the nostrils, and thus controlling the mind, senses and intelligence, the transcendentalist aiming at liberation becomes free from desire, fear and anger. One who is always in this state is certainly liberated.
PURPORT
Being engaged in Bhagavan consciousness, one can immediately understand ones spiritual identity, and then one can understand the Supreme Lord by means of devotional service. When one is well situated in devotional service, one comes to the transcendental position, qualified to feel the presence of the Lord in the sphere of ones activity. This particular position is called liberation in the Supreme.
After explaining the above principles of liberation in the Supreme, the Lord gives instruction to Arjuna as to how one can come to that position by the practice of the mysticism or yoga known as astanga-yoga, which is divisible into an eightfold procedure called yama, niyama, asana, pranayama, pratyahara, dharana, dhyana and samadhi.
In the Sixth Chapter of the Gita the subject of yoga is explicitly detailed, and at the end of the Fifth it is only preliminarily explained. One has to drive out the sense objects such as sound, touch, form, taste and smell by the pratyähära process in yoga, and then keep the vision of the eyes between the two eyebrows and concentrate on the tip of the nose with half-closed lids.
There is no benefit in closing the eyes altogether, because then there is every chance of falling asleep. Nor is there benefit in opening the eyes completely, because then there is the hazard of being attracted by sense objects.
The breathing movement is restrained within the nostrils by neutralizing the up-moving and down-moving air within the body. By practice of such yoga one is able to gain control over the senses, refrain from outward sense objects, and thus prepare oneself for liberation in the Supreme.
This yoga process helps one become free from all kinds of fear and anger and thus feel the presence of the Supersoul in the transcendental situation.