vijaydeep bhai ji
This is a recurring question. it comes around in Sikh forums in cycles like the 7-year locust.
I disagree with the determination that the Banee of Guru Nanak trumps any contradictions with the shabads of other Gurus, Bhats, Bhagats, sants. As soon as this question comes up it harkens to a debate about whether there is Guru Bani and Bhat Bani, etc.
There is nothing called Guru Bani and nothing called Bhat Bani. It is all Gurbani. There are no contradictions. Only apparent contradictions. When the argument is made the motive soon follows. The motive is 99.9 percent of the time an attempt to undermine the primacy, the unparalled standing of Sri Guru Granth Sahib as the Eternal Guru. These kinds of attempts are usually put forth by those who seek equal parkash of Bachittar Natak, and other historical texts, with Guru Granth. They consider Sri Guru Granth Sahib on a par with other "historically important texts." I read that just today. Sri Guru Granth Sahib is not a history book. Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=28415Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=28415
Although you may not agree with me, it is important for me to post my reply in a forthright way. A day, a week, a year from now, a member with some confusion on this point will need to read a straight answer.
Here is a good reference. Depend on it. One and Only Universal Guru