Chapter 8 Brahma Yoga Verse 8
Prayaanakaale manasaachalenaBhaktyaa yukto yogabalena chaiva;
Bhruvormadhye praanamaaveshya samyakSa tam param purusham upaiti divyam.
At the time of death, with unshaken mind, endowed with devotion and by the power of Yoga,
fixing the whole life-breath in the middle of the two eyebrows, he reaches that resplendent Supreme Person.
This sloka is the continuation of the previous sloka where Lord Krishna talks about the Supreme nature of God. The focus in this sloka shifts to the person from God. Here lord Krishna talks about what a person who is dying should do in order to attain the moksha. He says that a person at the time of his death should merge himself with devotion towards God and his mind should be unshaken from the thoughts of God, just like a person who does yoga with an unshaken mind. He then has to fix the breath and concentrate on the area in between his two eye-balls to reach the abode of Almighty.
Extending Interpretation to Mankind’s Life!
Here we are talking about the concept of Samadhi. Samadhi is one surest way of attaining moksha, and samadhi can be attained only when we shift our focus entirely to God. A person sits for meditation and the meditation he undertakes as a part of samadhi is his last meditation and he should not open his eyes anymore. In olden days, rishis go to samadhi when they feel that whatever they had to do in this mortal world is accomplished. A samadhi can be undertaken only by a spiritually evolved soul. Ordinary souls cannot even dream of attaining samadhi.
A person has to renounce everything and should have zero attachments, then only he will be eligible for samadhi. The best example one can take for samadhi is of Swami Vivekananda. He attained Mahasamadhi at an early age of 39. On July 4th 1902, Vivekananda  went to Belur math in Karnataka and met his disciples. Morning he meditated for few hours and after spending the entire day with them, he again went to meditation in evening after sunset and asked his disciples not to disturb him. He was in the yoga mudra when he attained samadhi somewhere in the night or early morning and his disciples found his lifeless body in the morning. His soul left the body through his crown chakra leaving a rupture in his brain. Samadhi is the surest way of reaching the Almighty at the time of death according to Lord Krishna.