Sage Veddharma had an ashram on the banks of river Godavari. He lived there with many of His disciples. Among them was a disciple named Deepak, who was his favourite. Deepak had utmost faith in his Guru.
The Sage once thought of testing the devotion of his disciples. He called all his disciples and told them, "In my previous birth, I committed a great sin. I have to bear the consequences of it. By doing spiritual practice in this birth, I have depleted some of it. But the remaining part of it has to be borne by me soon. It will affect my body in the form of a disease. I intend to stay in Kashi (a place in north India) during this period. Is anyone among you ready to come with me and serve my diseased body?" Hearing this, all the disciples remained silent except Deepak, who immediately replied, "Gurudev, I am ready to come to Kashi and serve you." The Guru replied, "Think twice before you commit to this. I will be in the diseased state, being blind and lame, for almost 2 years. Till then you will have to serve me." Deepak thought for a moment and said, "Gurudev, can I take your disease and stay in Kashi instead of you?" Hearing Deepak's words, the Sage was pleased and said, "No, you cannot, since each one has to bear the consequences of ones own deeds."
After a few days both of them left for Kashi. Within few days of reaching Kashi, the Sage's body started decaying. There were boils all over his body, his eyesight became weak, his movement was restricted. Deepak served his Guru truthfully and wholeheartedly. He helped his Guru in all his mundane activities. Sometimes Sage Veddharma would get angry with Deepak for no particular reason, but still Deepak remained calm and continued to serve the sage without any complaint.
Seeing Deepak's true Gurubhakti (devotion towards his Guru), Lord Shiva was pleased with and appeared before him. He said, "Ask for a boon and I shall fulfill your desire." Deepak replied, "I will ask my Guru about it." Deepak asked his Guru whether he should ask Lord Shiva to cure him of the disease. Sage Veddharma replied in the negative. So Deepak told Lord Shiva accordingly.
After a few days, Lord Vishnu appeared before him, praised him for his Gurubhakti and offered to grant him a boon. He replied, "Oh Lord! If you wish to grant me a boon, please grant me that my Gurubhakti increases." Lord Vishnu said, "You saw God in your Guru and served Him. You have proved that God and Guru are one and the same. You have thus increased the importance of both. I shower you with my blessings!" Thus, Deepak continued to serve his Guru. Sage Veddharma was very pleased with Deepak that he had passed the test. He blessed him and said, "You are my one true disciple. May you live long and your fame spread far and wide."