Nara-Narayana

Nara-Narayana (Sanskrit: नर-नारायण; nara-nārāyaṇa) is broken down where Nara means human and Narayana means the Supreme Divinity, or Vishnu. In the concept of Nara-Narayana, the human soul Nara is the eternal companion of the Divine Narayana. Any human being with an awakened consciousness of divinity in him and who works overall for the welfare of humanity is a Nara-Narayana, an incarnation of Vishnu on earth working for the preservation of dharma or righteousness.

Monier-Williams dictionary: Nara: the primeval Man or eternal Spirit pervading the universe (always associated with Nârâyana, son of the primeval man'), both are considered either as gods or sages and accordingly called devau.'

Depiction
They are depicted jointly or separately in images. When depicted separately, Nara is portrayed with two hands and wearing deer skin while Narayana is shown on the right in the usual form of Vishnu.

The legend
Sri Krishna and Arjuna are often referred to as Nara-Narayana in the Mahabharat. In a previous incarnation the duo were supposedly born as the sages Nara and Narayana,and who performed great penances at the holy spot of Badrinath.

Nara and Narayana were the Fifth Avatar of Lord Vishnu. The twins were sons of Dharma and his wife Murti (Daughter Of Daksha) or Ahimsa .They live at Badrika performing severe austerities and meditation for the welfare of the world. These two inseparable sages take avatars on earth for the welfare of mankind and to punish the wicked ones.

There was an asura named Shashtra Kavacha. He had got boon of having 1000 Kavachas(armours){the armours symbolizes different types of Ignorances, egos or evils); it will take 1000 Years to break each Kavacha, and the one ,who would break a Kavacha, would instantly die.

Hence, first Narayana pennaced for 1000 Yrs and Nara fought 1000 Years with ShahasrKavacha and after 1000 Years, Nara was able to break his one Kavacha. As Nara broke the Kavacha,he died. But Narayan due his penance of 1000 Yrs could get back life of Nara and Narayan starts fighting and Nara starts penance for the next 1000 years.

Nara and Narayana alternatively penace and fight for 1000 years and the cycle continued. At last, when they both were able to break 999 Kavachas. ShahastraKavacha hides himself behind the Surya with his last Kavacha due to fear that he would be killed by Nara and Narayana then. At this time, there is Pralaya on Earth due to the change of the Yuga. Thus ShashtraKavacha escapes death.

In Dwapara Yuga,he was reborn as Karna with Kavacha and Nar and Narayan as Arjun and Krishna respectively.

Birth of Urvashi
Once, sages Nara-Narayana was meditating in the holy shrine of Badrinath situated in the Himalayas.Their penances and austerities alarmed the gods, so Indra, the King of Devas, sent Kamadeva, Vasanta(spring) and apsaras (nymphs) to inspire them with passion and disturb their devotions. The sage Narayana took the flower and placed it on his thigh. Immediately there sprung from it a beautiful nymph whose charms far excelled those of the celestial nymphs, and made them return to heaven filled with shame and vexation. Narayana sent this nymph to Indra with them, and from her having been produced from the thigh (uru in Sanskrit) of the sage, she was called Urvashi.She occupied the pride of place in Indra’s court.

Badrinath
According to the Srimad Bhagavatam, "There in Badrikashram the Personality of Godhead (Vishnu), in his incarnation as the sages Nara and Narayana, had been undergoing great penance since time immemorial for the welfare of all living entities." (Srimad Bhagavatam 3.4.22)

In Badrinath Temple's sanctorium, to the far right side of the stone image of Badri-Vishala (or Badri-Narayana), are the images of Nara and Narayana.

Also, the Nara and Narayana peaks tower over Badrinath.

Mahabharata
According to Bhandarkar, the gods Nara-Narayana must be very famous at the time of the composition of the Mahabharata, since in the opening stanzas of different books obeisance is made to these two gods. In Vanaparvan(12. 46, 47), Krishna says to Arjuna,"O invincible one, you are Nara and I am Hari Narayana, and we, the sages Nara-Narayana, have come to this world at proper time.." In same Parva, chapter 30 (verse 1); Shiva says to Arjuna " In former birth you wer Nara and with Narayana as your companion, performed austerities for thousands of yers at Badari".