संस्कृत ससंदर्भ स्पष्टीकरणं कुरुत ।[3M]

Meaning: They attain eternal peace and not others.
Reference: The present shloka has been taken from कठोपनिषद्‌.
One which is eternal, which contains an element called Brahmatatva which developes different desires. The firm people sees them stable so only they attain permanent peace and not others.
The Brahmatatva is the creator of the universe which is eternal and exists in present, past and future and which is timeless and endless. Life spirit is soul. Those who see their own soul attain eternal peace and not others.

Meaning: All these shine with its light.
Reference: The present shloka has been taken from श्वेताश्वरोपनिषद्.
The shloka says that the sun does not shine by it self nor the moon and stars and the lightning shine by themselves. So how can the fire shine by itself? Only he (the supreme being) gives light to all of these. All of these shines with the light given by the supremebeing.

Meaning: Only the truth wins and not the untruth.
Reference: The fourth mantra of उपनिषद् रससुधा explains the importance of the truth. This mantra is from मुण्डकोपनिषद्. The mantra says that only the truth wins and not the untruth. The motion of an embodied soul spreads on the path of the truth. So those who die do not have to be reborn. The risis having fulfilled their desires cross that path and become free from the cycle of life and death. So it is the supreme asylum of the truth. That is why it is said that सत्यं ब्रूयात् प्रियं ब्रूयात्।

Meaning: One who knows Brahmatatva never fears.
Reference: The present shloka has been taken from 'तैत्तिरीयोपनिषेद'. This mantra says that the devotee who return without achieving any sort of joy with the mind realises Brahmatatva and exists in all movable and immovable matters. Due to the realisation of Brahmatatva, any sort of joy or misery does not affect him. According to the Gita, one who is free from all the vicissitudes and remains stable in any sort of joy or misery, focus on the supreme being and enjoys the bliss never fears from anybody.
Thus, being fearless and engrossed in bliss, he is the true scholar of Brahmatatva.