How did Krishna get Vishnu's Sharanga Bow?

Question

As I discuss in this answer, the divine architect Tvashta (AKA Vishwakarma) created two powerful bows, the Pinaka bow for Shiva and the Sharanga bow for Vishnu. Brahma once got Vishnu and Shiva to fight each other to find out who was more powerful, and Vishnu won merely by saying the word "hum", as described in the Bala Kanda of the Ramayana:

Once, all the gods were asking the Grandparent, Brahma, as to who is powerful and who is less powerful among the blue-throated Shiva and Vishnu, but the Grandparent Brahma on inferring the intent of gods started to create adversity among those two, Shiva and Vishnu, for the Grandparent is the best adherer of truthfulness, as truth cannot be demonstrated on hearsay evidence. Owing to their animosity then occurred a fierce and hair-raising war among Shiva and Vishnu, as each aspired victory for himself. By the 'hum' sound of Vishnu that ruinously overpowering longbow of Shiva is [fatigued], and the triple-eyed God, Mahadeva, is frozen.

Then gods along with the assemblages of sages and celestial caranas have come together and appealed to those two for appeasement in the matter of wielding authority, and then those two superior gods, Shiva and Vishnu, went into a state of amity. On seeing the bow of Shiva rendered inert by the mettlesomeness of Vishnu, from then on the gods along with the assemblages of sages deemed Vishnu to be the paramount.

Afterwards Shiva's Pinaka bow was given to the king Devarata of Mithila, and it was passed down by the kings of Mithila until it came into the possession of Sita's father Janaka. It was the Pinaka bow that was famously broken by Vishnu's incarnation Rama to win Sita's hand in marriage.

But my question is about the Sharanga bow of Vishnu. Vishnu gave the Sharanga bow to the sage Richika, who gave it to his son Jamadagni, who gave it to his son Parashurama, another incarnation of Vishnu. Now when Parashurama found out that Rama had broken the Pinaka bow, he confronted Rama and demanded that he string the Sharanga bow. Rama was successful, and afterwards Rama gave the Sharanga bow to Varuna the ocean god, as described in a later chapter of the Bala Kanda of the Ramayana:

On the departure of Rama of Jamadagni, that most glorious Rama of Dasharatha is quietened at heart, and he gave away that longbow of Vishnu into the hand of inimitable Rain-god [Varuna].

But my question is, what happened to the Sharanga bow after Varuna got it? Krishna seems to have gotten it at some point; he used it, e.g. in his battle against the demon Shalva, as described in the Srimad Bhagavatam:

Śālva then managed to strike Lord Kṛṣṇa’s left arm, which held His bow Śārṅga, and, amazingly, Śārṅga fell from His hand.

So how did Krishna get the Sharanga bow? Did Varuna give him at some point? As I discuss in this answer, when Arjuna and Krishna helped Agni fight against Indra, Varuna did give Krishna two weapons of Vishnu, the Sudarshana Chakra and the Kaumodaki mace. But the chapter of the Adi Parva of the Mahabharata doesn't mention the Sharanga bow.

Answer 1

I am giving the answer based on Mahabharata Udyog Parva, Bhagvat Yan Parva, chapter CLIX. According to this, Krishna got Sharang bow after killing Narakasur/Bhaumasur.

Baffling the nooses of Mura and slaying by his might that Asura, and vanquishing Naraka, the son of earth, Hrishikesa, while recovering the begemmed ear-rings of Aditi, with sixteen thousand girls and various kinds of jewels and gems, obtained that excellent bow called Sarnga.

And according to Shrimada Bhagvatam, Lord Krishna first killed Narakasur as mentioned in SB 10.59 and after then he killed Shalva as mentioned in SB 10.7 7.

Answer 2

In the Mahabharata it has been described that Pinaka was made by Shiva himself usind Manda Parvata as a bow and Vasuki as a string, not by Viswakarma. Shiva fought with Krishna and Arjuna using the Pinaka and you have missed the gist of this episode.

Book-7: Drona Vadha Parva:SECTION CCII

Vyasa narrates:

“Mahadeva thus accepted their request, moved by the desire of benefiting them, and said, ‘I will overthrow these Asuras. And Hara made the two mountains, viz., Gandhamadana and Vindhya, the two poles of his car. And Sankara made the earth with her oceans and forests his battle car. And the three-eyed deity made that prince of snakes, viz., Sesha, the Aksha, of that car. And that God of gods, the wielder of Pinaka, made the moon and the sun the two wheels of that vehicle. And the triple-eyed Lord made Elapatra and Pushpadanta, the two pins of the yoke. And the valiant Mahadeva made the Malaya mountains the yoke, and the great Takshaka the string for tying the yoke to the poles, and the creatures about him the traces of the steed. And Maheswara made the four Vedas his four steeds. And that lord of the three worlds made the supplementary Vedas the bridle-bits. And Mahadeva made Gayatri and Savitri the reins, the syllable Om the whip, and Brahma the driver. And making the Mandara mountains the bow, Vasuki the bowstring, Vishnu his excellent shaft, Agni the arrow-head, and Vayu the two wings of that shafts, Yama the feathers in its tail, lightning the whetting stone, and Meru the standard, Siva, riding on that excellent car which was composed of all the celestial forces, proceeded for the destruction of the triple city”.

Because of Rudra’s raudra (angry) form, Lord Vishnu uses the hunkārā sound (hum, which is Om) to calm him. Hearing that sound(nAda), Rudra goes into meditation. Thus his bow becomes jrambhita(frozen strung with arrow as it is) & Rudra becomes stambhita, going into samAdhi. This let everyone believe Vishnu is very sattvika and smart and Shiva is Bholenatha and Ashutosha.

This can be found in Mahabharata: Udyoga Parva: Bhagwat Yana Parva.

Sanskrit shloka can be found here:

8. संछिद्य मौरवान पाशान निहत्य मुरम ओजसा>

निर्जित्य नरकं भौमम आहृत्य मणि कुण्डले

9. षॊडश स्रीसहस्राणि रत्नानि विविधानि च

परतिपेदे हृषीकेशः शार्ङ्गं च धनुर उत्तमम

The English translation for this is given here:

Baffling the nooses of Mura and slaying by his might that Asura, and vanquishing Naraka, the son of the Earth, Hrishikesa, while recovering the begemmed ear-rings (of Aditi), with sixteen thousand girls and various kinds of jewels and gems, obtained that excellent bow called Sarnga.

The Sanskrit shloka can also be found in Mahabharata-BORI > Devanagari (and other Indian scripts from each sarga page) > ५ उद्योगपर्वम्:

सञ्छिद्य मौरवान्पाशान्निहत्य मुरमोजसा |

निर्जित्य नरकं भौममाहृत्य मणिकुण्डले ||८||

षोडश स्त्रीसहस्राणि रत्नानि विविधानि च |

प्रतिपेदे हृषीकेशः शार्ङ्गं च धनुरुत्तमम् ||९||

And then again it another version Varuna gave in to krishna as found here.