As quoted from Music Delighting An Ocean of Protectors by Kyabje Trijang Rinpoche:-
THE CLOSE RELATIONSHIP OF NECHUNG & DORJE SHUGDEN
When Dorje Dragden, overlord of the haughty ones
Repeatedly urged you fulfill your vow to arise
As a Dharma protector uncommon to the Geden,
You generated that mind of wrathful courage, praise to you!
Numerous times, during breaks between sessions of the great Manjushri Tsongkhapa's teachings at Ganden, there was a boy wearing white clothes who would come before him and demand, 'You must give me a helper!' Gyaltsab Je and Kedrub Choje knew the boy was an emanation of Pehar but never said anything. Since, at that time, Dulzin Dragpa Gyaltsen was the elder leader of the disciples receiving teachings, one day he said to the boy, 'It won't do for you to keep coming here and disturbing Je Lama when he is giving teachings! I'll give you whatever help it is that you want!' When he said that, the boy said, 'That ismy purpose! It is your help that I have been waiting to find! Now, here at this time, among all of the disciples, you have accepted!' Having said that, the boy became invisible and disappeared. At the time of Dulzin Dragpa Gyaltsen's later incarnation, Panchen Sonam Dragpa, the overlord of all of the haughty gods and spirits that exist in the world, Dorje Dragden, said to the Panchen,
'Manjusri of Blissful Intelligence has insisted that I should principally protect the Geden Teachings, but since I have already sworn to Padmasambhava that I would protect all of Buddha's Teachings in general, there is no way that I can principally protect only the Geden Teachings. Now Panchen, you yourself, among holders of the Geden Teachings these days, have the highest qualities of learning and realization. Not only that, you must arise as a wrathful protector of the Geden Teachings to fulfill the commitment you have previously made!'
At that time, saying only that he would check, the master did not commit himself. Then, when his later incarnation, Tulku Dragpa Gyaltsen, was urged by the Great Dharma King Nechung to remember his previous promise, Dragpa Gyaltsen asked, 'What promise?' seeming not to remember. Pehar gave him something from his hand, saying, 'If you take this and meditate, you will clearly remember.' Just as he said, by staying in seclusion, the master was reminded and generated fierce courage that did not shrink from arising in the form of a powerful fierce swift Dharma protector uncommon to the Geden in accordance with his previous promise. It is that demonstration of courage for which he is being praised in this verse.
The way that Nechung Gyalchen Dorje Dragden urged Panchen Sonam Dragpa to arise in the form of a fierce protector of the Geden Teachings is clear in the Drepung edition of the Panchen's biography. Moreover, if we examine carefully the last vision cited above, that Tulku Dragpa Gyaltsen had on the third day of the third month of the fire monkey year, before his sudden death at the age of thirty?eight in the fifth month of that year, from the second verse onwards, from 'Guide of devas and humans, Arhat Upagupta,' up to 'It is very important to understand...that this is the meaning of the drawn picture of samaya!' one can see it there, as well.
Also, in the great master Padmasambhava's Exhortation Address he said,
It's like this! Listen, O faithful king!
When Buddha came to this world, he was the Shravaka Upali,
When he passed into paranirvana he was called Upagupta,
In the city known as Bhava Bhadra, Excellent Nature.
To the east, in a region near China,
He will be the Shakya monk known as 'Lozang'.
Accordingly, going back to the last vision for a moment, not only had he received the command and commitment from his direct and lineage gurus such as Je Tsongkhapa who were of the same mental continuum as the Arhat Upagupta, it is also pleased him to hear it in the words of exhortation from that Protector of the Four Places, the Dharma King Nechung, and he had a vision of arising as a lord of the wrathful ones with an entourage of wrathful spirits and wrathful offerings.
Yet his wish to arise as a protector of Je Tsongkhapa's teachings and the opportunity of the circumstances that would converge between the Great Fifth Dalai Lama and Tulku Dragpa Gyaltsen, who were two great beings like the sun and the moon, seemed remote at the time. How quickly the commitments joined as one, he was enthroned, and so forth, as a great powerful wrathful protector of the Geden teachings, can generate conviction, as well.
