I felt I had to elaborate more on the mudra after receiving a query from a friend on Facebook yesterday.
It is in regard to whether or not the eyes should be open in Shambhavi Mudra.
The texts state very clearly that the eyes should be open. But we have to discern carefully here. According to my instructions given in the last post, the process of Shambhavi Mudra involves the instrumental layer, in other words the seeing itself and not the object seen. If we take Shambhavi Mudra in this way, it doesn't really matter whether the eyes are open or closed. The eyes are always seeing, whether it is dark or light, no matter what object is in front of the eyes. This process of the senses mirrors the nature of awareness or consciousness itself. This is the point. The eyes train us to come back into the nature of seeing itself. To come back to the Seer.
If we are focused on the object of perception we are stuck in the objective realm, no matter how high or lofty that object is. It could be the third eye, it could be God, it could be the highest thing imaginable. It is still an object of perception. This is why Patanjali divided the three modes of meditation into objective, instrumental and subjective forms. Meditation has to progress inwards towards the subject. And the instrumental level is a powerful bridge.
So ultimately whether the eyes are open or closed doesn't matter. However I have found according to the texts and my own experience that the eyes open in the beginning is better. Once you discover the depth of this mudra, feel free to close your eyes. Stay in the seeing even in the dark. This helps one to realize that outer and inner makes no difference. This is what the tantra teaches us.
In regards to whether this is right or wrong according to sampradaya I make no claims. I only speak from my own experience. It says in the Amanaskayogah "Shambhavi mudra is received by adishakti who is Uma (the Goddess)". What does this mean? To me it means that it can be received directly, deeply from the Self, from God. This is how it came to me after almost 25 years of practice in 2009, after 10 years of daily intensive Uddiyana Bandhas and Vicara practice. I felt in many ways that it was a deep fruit of intensive investigation and practice. But again I make no ultimate claim here. One can only ever speak from experience.
May you all investigate for yourselves to determine the Truth. Peace to you in that search.