Musnad Ahmad 920:10

Abdullah narrated to us, Abu Bakr Abdullah bin Muhammad bin Abi Shaybah narrated to me, Ubaydullah bin Musa narrated to us, from Isra'il, from Abu Ishaq, from Sa'id bin Jubayr, from Ibn Abbas, who said: We were with him, and the people said: "Nawf al-Shami claims that the one who went seeking knowledge is not Musa of the Children of Israel." Ibn Abbas was reclining, so he sat up straight and said: "Is that so, Sa'id?" I said: "Yes, I heard him say that." Ibn Abbas said: "Nawf has lied. Ubayy bin Ka'b narrated to me that he heard the Prophet, peace and blessings of Allah be upon him, say: 'May the mercy of Allah be upon us and upon Salih, may the mercy of Allah be upon us and upon the brother of 'Ad.' Then he said: 'While Musa was preaching to his people one day, he said to them: "There is no one on earth more knowledgeable than me." Allah revealed to him: "There is someone on earth who is more knowledgeable than you." The sign for that is that you should take a salted fish, and when you lose it, he is where you lose it.' So he took a salted fish, and he and his servant set out. When they reached the place they were commanded to go, they arrived at the rock. Musa went to search, and his servant placed the fish on the rock. It stirred and {took its course into the sea, slipping away} [Al-Kahf: 61]. His servant said: "When the Prophet of Allah comes, I will tell him." But {Satan made him forget} [Yusuf: 42]. They set out, and they were struck by the fatigue and exhaustion that befalls a traveler, though he had not been struck by the fatigue and exhaustion that befalls a traveler until he had passed what he was commanded to reach. Musa said to his servant: {Bring us our morning meal; indeed, we have suffered in this journey of ours, [much] fatigue} [Al-Kahf: 62]. His servant said to him: "O Prophet of Allah, {did you see when we retired to the rock? Indeed, I forgot} [Al-Kahf: 63] to tell you, {and none made me forget it except Satan} [Al-Kahf: 63], {and it took its course into the sea, slipping away} [Al-Kahf: 61]." He said: {That is what we were seeking} [Al-Kahf: 64]. So they returned, retracing their footsteps, following the tracks until they reached the rock. He found him covered with a garment of his. He greeted him, and he raised his head and said to him: "Who are you?" He said: "Musa." He said: "Which Musa?" He said: "Musa of the Children of Israel." He said: "I have been informed that you possess knowledge, and I wanted to accompany you." {He said, "Indeed, with me you will never be able to have patience"} [Al-Kahf: 67]. {He said, "You will find me, if Allah wills, patient, and I will not disobey you in any order"} [Al-Kahf: 69]. He said: "How can you be patient about that which you have no knowledge of?" He said: "I have been commanded to do it." He said: {You will find me, if Allah wills, patient} [Al-Kahf: 69]. {He said, "Then if you follow me, do not ask me about anything until I make to you about it mention." So they set out, until when they had embarked on the ship} [Al-Kahf: 71], those who were in it got out, and he stayed behind to tear it open. Musa said to him: "You tear it open to drown its people? {You have done a grave thing} [Al-Kahf: 71]. {He said, "Did I not say that with me you would never be able to have patience?" [Musa] said, "Do not punish me for what I forgot and do not cover me in my matter with difficulty"} [Al-Kahf: 72]. They set out until they came upon boys playing on the seashore, and among them was a boy who was cleaner than the other boys. He took him and killed him. Musa was startled at that and said: {Have you killed a pure soul for other than [having killed] a soul? You have certainly done a deplorable thing. [He] said, "Did I not tell you that with me you would never be able to have patience?"} [Al-Kahf: 74-75]. He felt a sense of shame before his companion and was embarrassed, so he said: {If I should ask you about anything after this, then do not keep me as a companion. You have obtained from me an excuse} [Al-Kahf: 76]. {So they set out, until when they came to the people of a town} [Al-Kahf: 77] who were stingy, {they asked its people for food} [Al-Kahf: 77]. Musa had been struck by hardship, yet they did not host them. {And they found therein a wall wanting to collapse, so he set it up} [Al-Kahf: 77]. Musa said to him, because of the hardship that had befallen them: "If you had wished, you could have taken payment for it." {He said, "This is parting between me and you"} [Al-Kahf: 78]. Musa grabbed the edge of his garment and said: "Tell me." He said: {As for the ship, it belonged to poor people working at sea} [Al-Kahf: 79]. {And there was after them a king who seized every ship by force} [Al-Kahf: 79]. So when he passed by it and saw it torn, he left it, and its owners patched it with a piece of wood and benefited from it. As for the boy, he was created on the day he was created as a disbeliever, and he had been cast with love from his parents. If they had obeyed him, he would have burdened them with {arrogance and disbelief} [Al-Kahf: 80]. {So we intended that their Lord should substitute for them one better than him in purity and nearer to mercy} [Al-Kahf: 81]. His father had intercourse with his mother, and she became pregnant, and she gave birth to one better than him in purity and nearer to mercy. {And as for the wall, it belonged to two orphan boys in the city, and there was under it a treasure for them, and their father had been righteous, so your Lord intended that they reach maturity and extract their treasure, as a mercy from your Lord. And I did it not of my own accord. That is the interpretation of that about which you could not have patience} [Al-Kahf: 82]."