how to serve teacher(Guru)

On the bank of Godavari, there was the Ashram of Angiras Rishi. Many disciples were being trained in this Ashram. One disciple named Sandeepak served his Guru, Veda Dharma, with great devotion. Once Veda Dharma Muni gathered his disciples together and said, "If you really love me, do as I bid you."
All replied, "Gurudev, we shall act as per your command, for one who doesn't obey his Guru, goes to hell and cannot get salvation."
The Guru said, "I have committed sins in my previous births. The effect of many of them has been wiped off by my penance, but still some of them are persisting. I will not get salvation unless I suffer the evil effects of these sins with my body. I, therefore, wish to go to Kashi, stay there and get rid of these sins. You have to attend on me and serve me during this period. One who is strong enough should undertake this hard task".
Sandeepak accepted this bid. Veda Dharma said, "It is better to get rid of the sins so long as one has sound health, otherwise they spread like poison. So I should go to a holy place and suffer the bad effects myself. Even Gods have to suffer, then how can a human being like myself avoid the same".
Sandeepak said, "Kindly tell me what I should do. I shall spare no pains in serving you."
Veda Dharma said, "I shall become blind, lame and a leper, you will have to serve me for 21 years in such condition. If you are resolute, then only you should accept this job."
Sandeepak said, "Gurudev, I resolve that I shall also be blind, lame and a leper and serve you devotedly and see that you get rid of all the sins".
Veda Dharma was much pleased with his words. He further said, "One should suffer the evil effects of one's sins oneself and should not allow the son or the pupil or anyone else to suffer for him. The sins will not be wiped off unless they are borne by one's own body. It is very taxing to serve a diseased person. So you will have to take troubles even more than myself. Please take me to Kashi and do serve me there."
Sandeepak assured his Guru and soon he took him to Kashi. They lived there at Kambaleshwar to the North of Mankarnika. The Muni took a bath in Mankarnika and worshiped Vishweshwar and began to suffer the pangs of diseases. As the time passed on, leprosy developed all over his body and he became blind losing his eyesight. His body was petrified and pus, blood and germs flowed out of it. He began to have fits also. Still Sandeepak took all pains to nurse his Guru with great devotion. He used to bring alms daily for his Guru, fed him and served him, thinking him to be Kashi Vishweshwar.
Veda Dharma being in a diseased condition became peevish by nature and often was enraged and spoke harsh words to his disciple, Sandeepak. Some day he would not take food, some day he would abuse him cruelly for bringing insufficient for undelicious alms. Some day he would throw away the food in anger and despair. Sometimes he would even beat him severely. Another time he would complain that he did not clean his body, wounds, clothes smeared with stool and urine and consequently he was much troubled by flies. When Sandeepak was attending on him, he would say why did he not go out for alms. In this way Sandeepak was harassed every now and then.
Yet Sandeepak tried his best to bring good delicious food and vegetables as directed by his Guru. Though he was living in Kashi, he never went to the Vishweshwar temple to worship and see the most holy shrine of Vishweshwar. Similarly he did not think of any other thing but he solely devoted himself to the nursing and giving best service to his Guru, whom he respected as God Shiva, Vishnu and Brahma. Though the Guru got enraged off and on, he did not retort harshly.
Seeing his such devoted service to his Guru, Kashi Vishweshwar was so pleased that he appeared before him and told him to ask for some favor or blessing. Sandeepak replied, "Without the approval of my Guru, I cannot ask for your blessings". He then came to his guru and said "Kashi Vishweshwar is pleased to offer me some blessing. If you permit me, I shall pray him to remove your physical pangs and give you sound health."
Hearing this, Veda Dharma was enraged. He said to Sandeepak "Do not pray Vishweshwar for my health. If I do not suffer these pangs, I will have to suffer in the next birth and this would abstract my path of salvation."
Sandeepak returned to Kashi Vishweshwar, and told him, " My Guru doesn't like me to accept any blessings from you." Being amazed Kashi Vishweshwar went to Shri Vishnu and reported this wonderful incident to him.
Hearing this, Shri Vishnu and Shri Kashi Vishweshwar desired to see this disciple and his Guru and so they both came to Kashi and approached Sandeepak. Shri Vishnu said, "Oh Sandeepak, I am pleased with your devotion to your Guru. You may ask for what ever you desire. I shall fulfill your wishes."
Sandeepak said, "Oh Narayan, even after undertaking penance in dense forest for infinite period, you disappoint your devotees. But when neither did I worship you, nor recite your name, why should you be pleased with me and ask me to have a boon from you?"
Shri Vishnu said, "Whatever devoted service you have rendered to your Guru, has been received by me. I love such disciples very much. I am under his influence and I willingly offer him my blessings. I like wife's devotion to her husband, bowing to Brahmins. Ascetics and Sanyasis, and such persons come to my place in the end."
Sandeepak said, "Oh Mahavishnu, I have full faith that I shall attain all knowledge of Vedas and Shastras from my Guru. As Guru is my God, Trimurties (Brahma, Vishnu and Mahesh) are within my reach, whatever blessings you give me; I shall be getting the same easily from my Guru. I am, therefore, serving my Guru devotedly."
On this Shri Vishnu said pleasingly, "Sandeepak, you are the best amongst all the disciples. You are my loving child. Shri Shiva and myself are pleased with your devotion. Ask for a boon."
Sandeepak said, "If you are so keen to favor me with your blessings, kindly give me such guidance as would enable me to serve my Guru with still more devotion."
Shri Vishnu said, "Amen! We offer you what you desire. You have known Guru and also experienced Par-Brahma in yourself. The word Guru contains only two alphabets; still it is the ocean of nectar. One, who dips into it even for a moment, will cross this worldly ocean. One who always remembers Guru is respected in all Lokas."
When Sandeepak went to his Guru, the Guru asked him, "What did Mahavishnu give you?"
Sandeepak replied,” I asked him to guide me to serve my guru with more devotion and he was pleased to give me this blessing. I wish I should serve you well and incessantly".
Hearing this Veda Dharma too was extremely pleased. He said,” You are the best of all the disciples. You should stay in Kashi. What ever you say will be true. You will receive the wealth of Kuber (God of Wealth), the miseries of those who remember you will come to an end".
The same moment, the body of Veda Dharma muni became healthy and bright. He had suffered from leprosy and other pangs only for testing his disciple.