Lord Vishnu and Lord Shiva are one and same.
Narahari was born in Devagiri. He learnt to read and write. But the way of the scholar was not to be his path. His father's profession called him, and he gave up his studies and began to help his father in the goldsmith profession. His surname was Sonar - the jeweler who makes golden ornaments. Narahari became proficient in the traditional art and gained a little name too as a good jeweler.
Subsequently, Narahari decided to shift to Pandharapur. Narahari loved Shiva dearly. He would pray to Him day and night. He would worship the Lord with great fervor. When in trouble, he would resort to this chosen deity, Shiva.
Pandharapur was a town of Krishna devotees. Narahari felt as if he were in a desert. To his utter dismay, he found that he was alone in the town. Everyone spoke about Panduranga, sang His praises, worshipped Him and adored Him. No one spoke of his dear Lord Shiva at all. Narahari thought, "Who is this Krishna? Who is Panduranga? And people are mad after this God. My Shiva can create a thousand such Pandurangas." What a noise these devotees of Panduranga make thought Narahari when he heard their keerthanas. Narahari stayed aloof. He decided not to bend his head before Panduranga. He earned fame as a very good goldsmith.
A rich man came to Narahari one day. He wanted to donate an ornament to Lord Panduranga and so requested Narahari to prepare one for him. He had decided on a silver ornament like a belt called 'kargota', in Marathi language to be tied around the Lord's waist. Narahari was ready, but didn't want to go to the Panduranga temple for measurements. He asked the customer to bring the measurements. The grand ornament was ready in a few days. When the rich man took it to the temple, the ornament did not fit the Lord. It was too tight.
The rich man and Narahari both were in a dilemma. The rich man had brought the correct measurements and Narahari made the ornament accordingly. By mysteriously it was too tight. Then the rich man asked Narahari himself to come over to the temple and take the measurements himself. Narahari was a bigot. He had taken a vow not to see any Vishnu image in his life. But the rich man suggested that Narahari's eyes could be tied up before the Lord and he can take measurement with his hands.
To go to a Vishnu temple, Narahari was hesitant, but the 'blinding' arrangement seemed appropriate. He prayed to Shiva to pardon him the transgression of stepping into a Vishnu temple and went with the rich man.
Once inside the temple, Narahari's eyes were tied up. Narahari began taking measurements of the God he did not like to see. He began to feel the image. Surprise of surprise the touch appeared to be something different. Was he touching the Shiva image? He moved his hands towards the face. He couldn't be mistaken because he being a goldsmith knew the Shiva image to be too well to be deceived. There was the matted hair; there were the three eyes! Yes. There was the name! He murmured; 'what's all this?' and tore the cloth away from his eyes. To his astonishment, it was the Panduranga image and not Shiva. But where were the snake, the three yes, and the matted locks?
He tied the bandage again like one mad and began to feel the image. Onlookers watched Narahari, behaving like a mad man inside the sanctum. Narahari's touch convinced him again that it was not a Vishnu image but a Shiva image. This time he carefully felt the image, and there was absolutely no doubt.
He removed the cloth once more. He opened his eyes. No. It was not he, but smiling Panduranga who had opened his dear devotee's eyes. Narahari Sonar was moved to torrential tears. He cried: "Oh Lord! Forgive this fool!" He knelt before the Lord and prostrated again and again.
(From the glorious life of Saint Narahari Sonar of Pandharapur)