In the chapter 29, Section 3 of Satarudra Samhita of Shiva Purana, the story of incarnation of Shiva as Krsnadashana is mentioned.
Ikshvaku and others were the sons of Manu Sraddhadeva of whom Nabhaga, was the ninth. Ambarisa was grandson of Nabhaga who was a devotee of Vishnu with whom the sage Durvasas was much pleased due to his devotion for Brahmins.
Nabhaga the son of Manu, highly intelligent, and with perfect control of his sense-organs stayed in the abode of his preceptors for studies for a long time. During this interval Ikṣhvaku and other sons had their due shares in the property without leaving any share for Nabhaga. At the behest of their father, the shrewd sons took their shares and enjoyed the kingdom with out any misery. They were fortunate.
After learning the Vedas with their sections and sub-sections, in due course, the Brahmacharin Nabhaga returned. On seeing his brothers Ikshvaku and others having taken their shares, Nabhaga desirous of his share told them affectionately.
“O my brothers you have taken your shares duly without leaving anything for me. I have now come for my share. Please give me mine.”
Then we had forgotten to allow your share. We shall certainly do it now. Our father is your share. Take him. On bearing the words of his brothers Nabhaga was surprised. He approached his father and said.
“O father, my brothers have taken their shares leaving me out. I had been to the preceptor’s abode for study as a student. When I returned I asked them to allot my share; they replied that you are my share. I have now come for that purpose.”
On hearing his words, his father Sraddhadeva was surprised. He consoled his son who was devoted
to truth and virtue.
O dear, do not pay heed to what they said. It was only to deceive you. I am not a share by any means, an instrument of enjoyment. Still since I have been given as a share by the deceitful persons I shall tell you the means of livelihood. Hear attentively. Brahmins are performing a sacrifice. Every sixth day the rites are marred.
O wise Nabhaga, you go there and praise them. Recite two Vaishvadeva sukatas there. That sacrifice will then become perfect. As soon as the sacrifice is concluded those Brahmins going heavenwards will give you delightedly the wealth left over in the sacrifice.
On hearing the words of his father, Nabhaga who considered truth as virtue went eagerly where the excellent sacrifice was on. In that sacrifice during the diurnal rites the intelligent son of Manu recited two Vaishvadeva suktas clearly. When the sacrifice was concluded the Angirasa Brahmins gave him the wealth left after the sacrifice.
Realising that he was taking the wealth left after the sacrifice, Shiva of divine sports manifested himself all of a sudden. He was beautiful in every limb, a glorious Puruṣa Kṛṣṇadarshana. It was to survey his emotional reaction and to bestow on him the perfect knowledge as his share that the lord manifested himself.
Lord Shiva desirous of testing Nabhaga the son of Manu approached from north and said: - “O man, who are you that take away my assets and wealth? Who has sent you here? Tell me the whole truth.”
On heaving his words, Nabhaga, son of Manu humbly replied to the Purusha Krsnadarshana. Nabhaga said:--
“This wealth of the sacrifice has been given to me by the sages. Why do you, O Krsnadarshana prevent me from taking it.”
On hearing these truthful words uttered by Nabhaga, the delighted purusha Krsnadarshana spoke:
“In our dispute the ultimate authority is your father. Go to him and ask him. What he says will be true and final.”
On hearing his words, the wise Nabhaga son of Manu, approached his father anxiously, and asked him about what he said.
On hearing what his son said, Manu Sraddhadeva remembered the lotus-like feet of Shiva and after recollecting spoke to him. Manu said:--
“Listen to my words: that Puruṣa is lord Shiva. Every object is his and particularly what is obtained from the sacrifice. That what is left over after the sacrifice is Shiva’s share. This argument is current among some intelligent people due to his will. Undoubtedly lord Shiva deserves everything. What then of the wealth left over in a sacrifice? More depends on the lord’s wish. O Nabhaga, the lord has come in that form in order to bless you. Go there. Propitiate him properly. Request him to forgive your fault. Bow to him well and eulogise him. That Shiva alone is the lord of all, the lord of sacrifice, the lord of everything. Vishnu, Brahma and other gods, Siddhas and the sages, O dear, are competent in their respective duties only due to his blessings. O foremost of my sons, go there quickly. Do not delay. Propitiate the great god, the lord of all by every means.”
After saying this, Manu Sraddhadeva, sent his son immediately to Shiva. After approaching him and bowing to him with palms joined in reverence and head bent down, the delighted Nabhaga of great intellect spoke to him humbly. Nabhaga said:--
“My father says that whatever there is in the three worlds is yours to be sure. What then about the wealth left over in a sacrifice? O lord, what I said before was done in error and ignorance. Please forgive the same. I propitiate you with my head bent down.”
After saying this, Nabhaga of dejected mind, eulogised lord Shiva Krsnadarshana with palms joined in reverence and with his head bent down. The pure-souled Sraddhadeva too with head bent and palms joined eulogised the lord and requested him to forgive his fault. In the meantime, Vishnu, Brahma, Indra and the gods, Siddhas and the sages came there. They were jubilant. They joined their palms in reverence. With great devotion they severally bowed down and eulogised.
Then the delighted Rudra, Krsnadarshana glanced at them with sympathetic eyes and smilingly spoke to Nabhaga. Krsnadarshana said:--
“What your father said is virtuous and true. You too spoke the truth. Hence you are good. There is no doubt in this. Hence I am delighted with your holy rites. Sympathetically I am conferring on you the eternal Brahman, the perfect knowledge. Be great and wise, O Nabhaga, along with the Brahmins immediately. Take all this wealth granted by me out of compassion. O intelligent one, enjoy all pleasures without any aberration. By my grace you will attain the good goal along with the Brahmin sacrifices.”
After saying this, lord Shiva vanished them itself even as all were watching. Vishnu, Brahma, the gods and all others went to their respective abodes after joyously bowing to that direction. Sraddhadeva too, accompanied by his son, went joyously to his abode. After enjoying extensive pleasures he went to Shiva’s city in the end.