Can someone tell me how guru gobind singh ji passed away?
Nawab Wazir Khan of Sirhind had felt concerned at the Emperor's conciliatory treatment of Guru Gobind Singh. Their marching together to the South made him jealous, and he charged two of his trusted men with murdering the Guru before his increasing friendship with the Emperor resulted in any harm to him. These two pathans Jamshed Khan and Wasil Beg are the names given in the Guru Kian Sakhian pursued the Guru secretly and overtook him at Nanded, where, according to Sri Gur Sobha by Senapati, a contemporary writer, one of them stabbed the Guru in the left side below the heart as he lay one evening in his chamber resting after the Rahrasi prayer. Before he could deal another blow, Guru Gobind Singh struck him down with his sabre, while his fleeing companion fell under the swords of Sikhs who had rushed in on hearing the noise. As the news reached Bahadur Shah's camp, he sent expert surgeons, including an Englishman, Cole by name, to attend on the Guru. The wound was stitched and appeared to have healed quickly but, as the Guru one day applied strength to pull a stiff bow, it broke out again and bled profusely. This weakened the Guru beyond cure and he passed away on Kattak sudi 5, 1765 Bk/7 October 1708. Before the end came, Guru Gobind Singh had asked for the Sacred Volume to be brought forth. To quote Bhatt Vahi Talauda Parganah Jind: "Guru Gobind Singh, the Tenth Master, son of Guru Teg Bahadur, grandson of Guru Hargobind, great-grandson of Guru Arjan, of the family of Guru Ram Das Surajbansi, Gosal clan, Sodhi Khatri, resident of Anandpur, parganah Kahlur, now at Nanded, in the Godavari country in the Deccan, asked Bhai Daya Singh, on Wednesday, 7 October 1708, to fetch Sri Granth Sahib. In obedience to his orders, Daya Singh brought Sri Granth Sahib. The Guru placed before it five pice and a coconut and bowed his head before it. He said to the sangat, "It is my commandment: Own Sri Granthji in my place. He who so acknowledges it will obtain his reward. The Guru will rescue him. Know this as the truth".
Guru Gobind Singh thus passed on the succession with due ceremony to the Holy Book, the Guru Granth Sahib, ending the line of personal Gurus. "The Guru's spirit," he said, "will henceforth be in the Granth and the Khalsa. Where the Granth is with any five Sikhs representing the Khalsa, there will the Guru be." The Word enshrined in the Holy Book was always revered by the Gurus as well as by their disciples as of Divine origin. The Guru was the revealer of the Word. One day the Word was to take the place of the Guru. The inevitable came to pass when Guru Gobind Singh declared the Gura Granth Sahib as his successor. It was only through the Word that the Guruship could be made everlasting. The Word as contained in the Guru Granth Sahib was henceforth, and for all time to come to be the Guru for the Sikhs.
http://www.sikh-history.com/sikhhist/gurus/nanak10.html
Another source,
The Guru's wound was immediately stitched by the Emperor's European surgeon and within a few days it appeared to have been healed. Soon after when the Guru tugged at a hard strong bow, the imperfectly healed wound burst opened and caused profuse bleeding. It was now clear to him that the call of the Fatherfrom Heaven had come and he, therefore, gave his last and enduring message of his mission to the assembly of the Khalsa. He then opened the Granth Sahib, placed five paise and a coco-nut before it and solemnly bowed to it as his SUCCESSOR, GURU GRANTH SAHIB. Saying 'Waheguru ji ka Khalsa, Waheguru ji ki Fateh', he circumambulated the sacred volume and proclaimed," O beloved Khalsa, let him who desireth to behold me, behold the Guru Granth. Obey the Granth Sahib. It is the visible body of the Gurus. And let him who desireth to meet me, diligently search its hymns." He then sang his self-composed hymn:
"Agya bhai Akal ki tabhi chalayo Panth
Sabh Sikhan ko hukam hai Guru manyo Granth
Guru Granth Ji manyo pargat Guran ki deh
Jo Prabhu ko milbo chahe khoj shabad mein le
Raj karega Khalsa aqi rahei na koe
Khwar hoe sabh milange bache sharan jo hoe."
Translation of the above:
"Under orders of the Immortal Being, the Panth was created. All the Sikhs are enjoined to accept the
Granth as their Guru.
Consider the Guru Granth as embodiment of the Gurus. Those who want to meet God, can find Him
in its hymns. The Khalsa shall rule, and its opponents will be no more, Those separated will unite and
all the devotees shall be saved."
He, in grateful acknowledgement of the spiritual benefactions of the founder of his religion, uttered a Persian distich, the translation of which is:
"Gobind Singh obtained from Guru Nanak
Hospitality, the sword, victory, and prompt assistance."
(These lines were impressed on a seal made by the Sikhs after the Guru left for his heavenly abode, and were adopted by Ranjit Singh for his coinage after he had assumed the title of Maharaja in the Punjab)
He then left for his heavenly abode. The Sikhs made preparations for his final rites as he had instructed them, the Sohila was chanted and Parsahd (sacred food) was distributed.
While all were mourning the loss, a Sikh arrived and said," You sup pose that the Guru is dead. I met him this very morning riding his bay horse. After bowing to him when I asked whither he was going, he smiled and replied that he was going to the forest on a hunting excursion."
The Sikhs who heard this statement arrived at the conclusion that it was all the Guru's play, that he dwelt in uninterrupted bliss, that he showed himself wherever he was remembered. He who treasures even a grain of the Lord's love in his heart, is the blessed one and the Guru reveals himself to such a devotee in mysterious ways. Wherefore for such a Guru who had departed bodily to Heaven, there ought to be no mourning.
The Master returned to his Eternal Home on the 5th of the bright half of Katik, Sambat 1765 (7th October, 1708 A.D.). He was 42 years of age.
http://allaboutsikhs.com/gurus/gurugobind9.htm