The eighth guru was the second son of Har Rai, but he died when a child and too young to leave any mark on in his favour and also in favour of the next guru for having altered a line of the Granth to please the emperor Aurangzeb.
Jaidev is better known as the author of the Gitagobind, which was translated by Sir Edwin Arnold, than as a religious reformer; but in the Adi Granth are found two hymns of his in the Prakrit language of the time, in which he represents God as distinct from nature, yet everywhere present.
The Nanakpanti Sikhs do not wear the hair long, nor use any of the outward signs of the Sikhs, though they reverence the Granth Sahib and above all the memory of their guru.
It was Guru Arjan who compiled the Granth or Sikh Bible, out of his own and his predecessors' compositions.
Ideas of revolt and reform of decadent systems are always in the air, it may be for centuries, until some one man bolder than the rest stands out to give them free expression; and as John the Baptist preceded Jesus Christ, so Nanak was preceded by several reformers, whose writings are incorporated in the Granth itself.
The doctrines of Sikhism as set forth in the Granth are that it prohibits idolatry, hypocrisy, class exclusiveness, the concremation of widows, the immurement of women, the use of wine and other intoxicants, tobacco-smoking, infanticide, slander and pilgrimages to the sacred rivers and tanks of the Hindus; and it inculcates loyalty, gratitude for all favours received, philanthropy, justice, impartiality, truth, honesty and all the moral and domestic virtues upheld by Christianity.
As all the guru's sons predeceased him, and as he was disappointed in his envoy Banda, he left no human successor, but vested the guruship in the Granth Sahib and his sect.
The religious creed of Guru Govind Singh was the same as that of Guru Nanak: the God, the guru and the Granth remained unchanged.