Makkan Shah was devoted man who was a rich traveller. Once he was sailing in his ship a great storm almost sank his ship. He prayed to the Guru to save him and miraculously the storm calmed. He promised to give the Guru an offering...
Once Guru Nanak went on a long walk with all his dicsiples. As they were walking some people found money on the ground and they went home. After a long, long distance only two Sikhs were left. Guru Nanak told them to eat a dead body. One Sikh couldn't do it, but Bhai Lehna humbly obeyed. Lehna's devotion surpassed all tests. He was so devoted he was like an 'ang' a limb of the Guru.
The great Emperor of India, King Akbar, went to go visit the Guru. Guru Amar Das Dev ji wouldn't see the visiting royalty until his guest had eaten in the Guru's langar. So this great ruler of the whole land sat along side all kinds of common people and ate langar. Emperor Akbar was impressed that the Guru served so many people, and was humbled that Guru Amar Das didn't consider anyone higher or lower.
Mata Ganga who was the wife of Guru Arjan Dev Ji, could not have a baby, so she went to ask Bhai Budha for this blessing. After rejecting her once, Bhai Budha accepted her offering. As he ate he crushed an onion with his fist, he said, "Your son will be a master of heaven and earth. He will crush enemies like I crushed this onion."
Humayun went to Guru Angad to get blessing and restore his rule. He got angry that the Guru didn't give him respect so he went to kill the Guru. Then Guru Angad told him that he is quick to kill men of God, but couldn't defend his on kingdom. Humayun bowed to the Guru and asked forgiveness.