Secondly the word 'Guru' is also used for Guru Nanak as he was the Embodiment of God's Light:
'Guru Nanak is the perfect Guru, With the true Guru I meditateth upon God.' (Ramkali Mohalla 4, p-882) 'Guru Nanak is the true Guru, The true Guru taketh me to God.' (Kanra Mohalla 4, p-1310) 'The Guru and God are one , Divine Master pervadeth everywhere.' (Sri Rag Mohalla 5, p-53)
Thirdly the word 'Guru' is used for Gurbani, the Divine Word. Since Gurbani came direct from God, and as there is no difference between God and His order (Divine Word), Gurbani is Guru too:
'The Word is the Guru, And the Guru is the Word, The Guru's Word is full of life-giving Elixir, Whosoever shall obey, what the Word commandeth, Verily he shall get salvation.' (Nat Mohalla 4, p-982) 'The Word is the True Guru and True Guru is the Word, And the Word revealeth the path of salvation.' (Kanra Mohalla 4, p-1310)
DIVINE WORD CAME DIRECT FROM GOD:
Guru Granth Sahib does not narrate the life story of Guru Nanak, but each and every word is dedicated to the Glory of the Almighty God only. It is not a reproduction of earlier religions, but the Divine Word (Gurbani) came to the Gurus direct from God. Guru Nanak stated that it was not his philosophy, it was not his understanding and it was not his thinking, but the Word was coming to him direct from God and he was simply delivering His message to the world. As he confirms:
'O Lalo, as comes the Divine Word from Lord to me, So do I narrate it.' (Tilang Mohalla 1, p-722) 'I have said what Thou commandeth me to say.' (Wadhans Mohalla 1,p-566)
This was repeatedly confirmed and emphasized by all the Gurus in their Bani such as:
'From God springs ambrosial Gurbani The exalted Guru narrates and preaches the same to world.' (Majh Mohalla 3, p-125) 'This Word comes from Him, Who hath created the World.' (Mohalla 4, p-306) 'This Word that hath come from God, It dispelleth all woes and worries.' (Sorath Mohalla 5, p-628) 'I speak but the Will of the Lord, For, the Lord's devotee narrateth the Word of the Lord.'(Sorath Mohalla 5, p-629) 'Whatever the Lord hath instructed me, Hear, O my brother.' (Tilang Mohalla 9, p-727)