Guru Yoga is a must within Buddhadharma.
Here gives Geshe Gelek Jinpa Rinpoche a brief explanation about Guru Yoga in Bon which doesn' t differ much from the other Traditions.
Also remarkable is his vision about the Ngondro 4 times 100.000 for many Dzogchenpas sometimes / maybe, seen as unneeded.
But it is all seen in the vision of a Bon Dzogchen Master in the Lineage of the ZZNG Dzogchen cycle of Teachings, maintained at Triten Norbutse Monastery and elsewhere.
Guruyoga according Geshe Gelek.
Afterwards, you need to think that your Root Master is Buddha, that he has Knowledge and power and Wisdom; we imagine our Root Guru like Buddha. You can think he is just like an ordinary person, but all the past Masters got their Teachings from their Teacher and got realization, Enlightenment. It is the same with us – we receive Teachings from our Teacher, practice with meditation and finally achieve Enlightenment, so therefore we need to imagine our Root Guru is the same level as Buddha.
In the same way, if you are ill, you can pray to your Master to free you from your illness and it can work. Or sometimes you go to meditation and it is very difficult to stay in the Natural State or with Compassion, or whatever meditation you are doing – your mind is too busy. At that time, visualize and pray to your Master and ask him, ‘Please, help me!’ Your Master can help you.
You might think, ‘Why should I visualize my Master? He is human, I can see him!’ but before, many Masters said that if you visualize your Master and pray to him, do Guru Yoga, then that is the root of practicing meditation. However you imagine your Master – as a Buddha, Dharmakaya, Sambhogakaya, whatever – that is the realization you could get. The Lineage is also very important, it has been unbroken from the Dharmakaya to your Master, so the blessings come through the Lineage Masters. You need to think this. You also need to think that your Master is very kind and that what he says is very important, then you can understand. And if he gives Teachings, you must think they are very important and then you will be able to do practice very easily because you believe what he says.
That is why we should believe that our Master is the same level as Buddha.
How do you visualize him? Everyone already knows, you have received Teachings from His Holiness, but I will say it again. You can visualize what you want to, what is easy for you – Tapihritsa, Shenlha Ökar etc. We usually say he is in front of you, or above your head. So visualize your Deity or Buddha and imagine that it is your Root Master. He looks like Tapihritsa or Tonpa Shenrab, but he is Light, Compassion, Wisdom, Power and so whatever you need, he can give you.
So you just think this and light rays come from him to all sentient beings and eliminate all negative thoughts so all sentient beings are free from all negativity, illnesses etc. Then you receive Knowledge from your Master’s body, speech and mind to your body, speech and mind. Wisdom Fire comes from our Master’s Body to ours and so our body is purified of all negativity. Then Nectar Water comes from his Speech into our Central Channel and purifies all our negativity and karma of speech. Then at our chest level we receive Five Lights which clean away the Five Negativity, so everything is purified and realized.
Visualize your Master above your head, and then when you go to sleep he comes down your Central Channel to your heart level and you concentrate there and go to sleep. When you wake up the next morning, he re-emerges above your head. That is Guru Yoga.
Detail from Ngondro teachings by Ghese Gelek Jinpa Rinpoche:
When we find an excellent quality Root Master, we first need to practice the Preliminaries. Why? – To purify our mind. Generally we talk about pure and impure mind, so when you receive Teachings on Preliminaries, you focus and practice and can purify your own impure mind. There are four different things to do: Compassion, Bodhichitta, Refuge and Mandala Offering. When we receive Teaching on the Preliminaries and try to listen, study and meditate, often our mind and motivation are disturbed. Before you were a normal person, sometimes more positive, sometimes more negative, but then you become more positive and your Compassion increases, and that means that you received the Preliminaries in an excellent way. If we meditate, listen to the Teachings and study but our mind remains impure with the Five Poisons and negative emotions – jealousy, pride etc - then that means our mind has not been purified. Traditionally we say you should do a hundred thousand prostration and recitations. There are many different mantras and prayers to recite, but we shouldn’t just recite them; we need to change inside. If you have done a hundred thousand but still always follow anger, attachment etc, then you can’t say you have finished the Preliminaries. People say that the Preliminaries are easy, but actually if you read a Dzogchen text from the beginning to the end, it always says you must purify your mind and then afterwards you will become a Dzogchen practitioner; if you haven’t purified your mind, you will not be a good Dzogchen practitioner.