Here is the story of Nabi Khidir as and Nabi Musa a.s. You can find it in the Quran from surah Al-Khaf verses 60 to 82. It was also narrated by Ibn 'Abbas Ubay bin Ka'ab as what he heard from our Prophet Muhammad s.a.w. This is my simplified version of the story. 8)

It was said that it started with Nabi Musa as standing before the Bani Isra'il. He asked if anyone knew who was the most knowledgeable among them. "Me" said Nabi Musa as. At this point, Allah swt reminded him that there was one who was more knowledgeable than Nabi Musa and he lived where two seas meet. A lesson we learn here is about humility. No matter how smart or intelligent we think we are, there will always be someone who is better than us.

Nabi Musa wanted to meet this person who Allah mentioned. He wanted to learn and hoped to be as knowledgeable as that person. So Allah told him to bring a fish and and he would find that knowledgeable person at the place where the fish freed itself into the sea. Nabi Musa as was hungry for knowledge. Even a Nabi who Allah had given great knowledge and wisdom wanted to know more that what he knew.

So off Nabi Musa went together with one of his follower. Nabi Musa said "I will not give up until I reach the place where the two seas meet even if it will take years to find it." Nabi Musa was determined to meet this person. However, when they reached the place where the two seas meet, Nabi Musa's follower saw the fish which made its way to the sea. But he forgot to tell Nabi Musa. They had walked a distance from that place when remembered and told the incident to Nabi Musa. So they traced their way back to the place.

There, they met a man dressed in white. They exchanged greetings. "Who are you?" asked Nabi Khidir. " I am Musa" said Nabi Musa. "Musa from Bani Isra'il?" Nabi Khidir asked. "Yes, I have come to learn from you." Nabi Musa replied.

Nabi Khidir said " You will have no patience. Allah has given me a part of His knowledge that He did not give you and He gave you a part of His knowledge that He did not give me." Nabi Musa so eager to learn from Nabi Khidir said "Insya'allah, I will have patience." Then Nabi Khidir agreed on condition that Nabi Musa would not ask him questions until he, himself, tell Nabi Musa about it.

So off they went on their journey of knowledge. During their journey, they took a boat. Nabi Khidir made a hole in that boat. Seeing that, Nabi Musa asked "Why did you damage the boat and may drown people who use it?" Nabi Khidir just replied "Did I not tell you that you have no patience?" Nabi Musa apologised and kept quiet.

Then, they went on until they met a boy and Nabi Khidir killed the boy. Nabi Musa was shocked and said "Why did you kill that innocent child? Isn't that an evil thing?" Once again, Nabi Khidir said" Didn't I tell you that you have no patience?" Once again, Nabi Musa apologized and said that if ever he asked anything again after this, Nabi Khidir have a reason not be teach him.

Then, they continued their journey and they came to a town. They asked the people for food but they were not given any. There, they found a wall that were about to fall. Nabi Khidir repaired the wall. Nabi Musa said "If you wanted, you could have asked these people to pay for your service since they did not even treat as well as their guests."

Nabi Khidir then told Nabi Musa that the time as come for them to part since Nabi Musa did not follow his rules. But before that, he would explain why he did those things along the way. "The boat belonged to poor people and it is used to help them earn a living. In that country live an evil king who will take every boat on the land. If the boat is damaged, the king will not take it and the people will still be able to go to the river to earn a living. I killed the boy because his parents are good people and the boy will grow up into someone who is disobedient and ungrateful to Allah and other people. Allah will in turn give them a son who is better than this one. And I repaired the wall because beneath the wall is a treasure that belong to 2 orphans, buried by their father. If the wall had falled, the treasure would be discovered by the people of the town. So I repaired the wall such that the orphans would recover them when they grow older."

Hearing that, Nabi Musa as realised the "hikmah" behind things that had happened. Nabi Khidir was given a gift by Allah to forsee what will happen in the future. Something that seem so wrong now, may actually be right in the future.