Gyani Udham Singh Ji wrote a book many years ago about Ikonkaar and the power of Satguru Sri Guru Nanak Dev Ji Maharaj's bani. Within this book Gyani Ji wrote the following sakhi which he experienced with his own eyes:
One time there was a Nihang Singh who used to live at a Gurudwara Sahib in a village in India. Gyani Udham Singh Ji visited this Gurudwara Sahib and saw the Nihang Singh Ji rush outside through the doors of the Gurudwara Sahib as if his very life depended on it.
After a while the Nihang Singh would return to the darbar of Dhan Dhan Dhan Dhan Dhan Satguru Sri Guru Granth Sahib Ji Maharaj and take his place within the sangat. After a certain time had elapsed the Nihang Singh Ji would rush outside once again.
Gyani Udham Singh Ji began to wonder what the Nihang Singh Ji was doing and decided to follow him outside the next time he rushed out. When the Nihang Singh Ji did so Gyani Udham Singh Ji saw him run into a field behind the Gurudwara Sahib (facing Guru Granth Sahib Ji) and stand with his hands together before matha teking. After remaining like this for a while the Nihang Singh Ji would then get up and walk back towards the Gurudwara Sahib.
When Gyani Udham Singh Ji saw this he thought in his mind that the Nihang Singh has probably taken some bhang and does not know what he is doing. But then he thought that he should ask the Nihang Singh Ji why he does what he does.
The next time the Nihang Singh Ji rushed out Gyani Udham Singh Ji quickly stopped him and said, "Where are you going?" The Nihang Singh Ji quickly replied, "Satguru Sri Guru Gobind Singh Ji Maharaj and the fauj are waiting, I have to get ready!"
Gyani Udham Singh Ji still thought that the Nihang Singh Ji was under the influence of nasha. However when he sat near to the Nihang Singh Ji in the darbar of Guru Sahib all he could hear vibrating from the Nihang Singh was, "Waheguru, Waheguru, Waheguru, Waheguru, Waheguru, Dhan Guru Gobind Singh Ji Maharaj, Waheguru, Waheguru, Waheguru, Waheguru, Waheguru, Dhan Guru Gobind Singh Ji Maharaj".
As Gyani Udham Singh Ji heard this he saw the Nihang Singh Ji bow before Maharaj and say, "This Fauji is ready now" as he ran through the Gurudwara Sahib doors and into the field where he placed his head. Only this time the Nihang Singh Ji didn't get up.
When the Sangat saw this they gathered around and were left in a state of shock. One of the old sevadaars of the Gurudwara Sahib stepped outside of the crowd and said that this Nihang Singh Ji was no ordinary Singh but a Bandagiwala Mahapursh who choose to remain Gupt.
The sevadaar said that he used to see the Nihang Singh Ji daily but the Singh would remain absorbed in Sri Mool Mantar Sahib Ji, Sri Gurmantar Sahib Ji and Seva.
Dhan Sri Guru Gobind Singh Ji Maharaj.