Gita Chapter 8.16 to 8.20

Aabrahmabhuvanaallokaah punaraavartino’rjuna;
Maamupetya tu kaunteya punarjanma na vidyate.
16. (All) the worlds, including the world of Brahma, are subject to return again, O Arjuna! But he who reaches Me, O son of Kunti, has no rebirth!

Sahasrayugaparyantam aharyad brahmano viduh;
Raatrim yugasahasraantaam te’horaatravido janaah.
17. Those who know the day of Brahma, which is of a duration of a thousand Yugas (ages), and the night, which is also of a thousand Yugas’ duration, they know day and night.

Avyaktaadvyaktayah sarvaah prabhavantyaharaagame;
Raatryaagame praleeyante tatraivaavyaktasamjnake.
18. From the unmanifested all the manifested (worlds) proceed at the coming of the “day”; at the coming of the “night” they dissolve verily into that alone which is called the unmanifested.
COMMENTARY: Coming of the “day’ is the commencement of creation. Coming of the “night” is the commencement of dissolution.

Bhootagraamah sa evaayam bhootwaa bhootwaa praleeyate;
Raatryaagame’vashah paartha prabhavatyaharaagame.
19. This same multitude of beings, born again and again, is dissolved, helplessly, O Arjuna, (into the unmanifested) at the coming of the night, and comes forth at the coming of the day!

Parastasmaat tu bhaavo’nyo’vyakto’vyaktaatsanaatanah;
Yah sa sarveshu bhooteshu nashyatsu na vinashyati.
20. But verily there exists, higher than the unmanifested, another unmanifested Eternal who is not destroyed when all beings are destroyed.
COMMENTARY: Another unmanifested Eternal refers to Para Brahman, which is distinct from the unmanifested (primordial Nature), and which is of quite a different nature. It is superior to Hiranyagarbha (the creative Intelligence) and the unmanifested Nature because It is their cause. It is not destroyed when all beings from Brahma down to a blade of grass are destroyed.

Gita Chapter 6.16 to 6.20

Naatyashnatastu yogo’sti nachaikaantamanashnatah;
Na chaatiswapnasheelasya jaagrato naiva chaarjuna.
16. Verily Yoga is not possible for him who eats too much, nor for him who does not eat at all; nor for him who sleeps too much, nor for him who is (always) awake, O Arjuna!

Yuktaahaaravihaarasya yuktacheshtasya karmasu;
Yuktaswapnaavabodhasya yogo bhavati duhkhahaa.
17. Yoga becomes the destroyer of pain for him who is always moderate in eating and recreation (such as walking, etc.), who is moderate in exertion in actions, who is moderate in sleep and wakefulness.

Yadaa viniyatam chittamaatmanyevaavatishthate;
Nihsprihah sarvakaamebhyo yukta ityuchyate tadaa.
18. When the perfectly controlled mind rests in the Self only, free from longing for the objects of desire, then it is said: “He is united.”

COMMENTARY: Without union with the Self neither harmony nor balance nor Samadhi is possible
.
Yathaa deepo nivaatastho nengate sopamaa smritaa;
Yogino yatachittasya yunjato yogamaatmanah.
19. As a lamp placed in a windless spot does not flicker—to such is compared the Yogi of controlled mind, practising Yoga in the Self (or absorbed in the Yoga of the Self).
COMMENTARY: This is a beautiful simile which Yogis often quote when they talk of concentration or one-pointedness of mind.

Yatroparamate chittam niruddham yogasevayaa;
Yatra chaivaatmanaa’tmaanam pashyannaatmani tushyati.
20. When the mind, restrained by the practice of Yoga, attains to quietude, and when, seeing the Self by the Self, he is satisfied in his own Self,

Gita Chapter 3.41 to 3.43

Tasmaat twam indriyaanyaadau niyamya bharatarshabha;
Paapmaanam prajahi hyenam jnaana vijnaana naashanam.
41. Therefore, O best of the Bharatas (Arjuna), controlling the senses first, do thou kill this sinful thing (desire), the destroyer of knowledge and realisation!

Indriyaani paraanyaahur indriyebhyah param manah;
Manasastu paraa buddhir yo buddheh paratastu sah.
42. They say that the senses are superior (to the body); superior to the senses is the mind; superior to the mind is the intellect; and one who is superior even to the intellect is He—the Self.

Evam buddheh param buddhwaa samstabhyaatmaanam aatmanaa;
Jahi shatrum mahaabaaho kaamaroopam duraasadam.
43. Thus, knowing Him who is superior to the intellect and restraining the self by the Self, slay thou, O mighty-armed Arjuna, the enemy in the form of desire, hard to conquer!
COMMENTARY: Restrain the lower self by the higher Self. Subdue the lower mind by the higher mind. It is difficult to conquer desire because it is of a highly complex and incomprehensible nature. But a man of discrimination and dispassion, who does constant and intense Sadhana, can conquer it quite easily.

Hari Om Tat Sat
Iti Srimad Bhagavadgeetaasoopanishatsu Brahmavidyaayaam
Yogashaastre Sri Krishnaarjunasamvaade
Karmayogo Naama Tritiyo’dhyaayah
Thus in the Upanishads of the glorious Bhagavad Gita, the science of the Eternal, the scripture of Yoga, the dialogue between Sri Krishna and Arjuna, ends the third discourse entitled:

“The Yoga of Action”