Saeed bin Jubayr reported,

I said to Ibn Abbas that Ubayy had said, "I wrote it down from Bahz and Ibn Uyayna, even though Nawf claims that Musa is not the companion of Khidr."Ibn Abbas replied, "The enemy of Allah has lied. Ubayy bin Kaab narrated to us from the Prophet ﷺ who said, Musa stood up to address the Children of Israil and was asked, 'Who is the most knowledgeable of people?' He answered, 'I am.' So Allah reproached him for not referring the knowledge back to Him, and said, 'Rather, a servant of Mine at the junction of the two seas is more knowledgeable than you.'Musa asked, 'My Lord, how can I reach him?'Allah said, 'Take a fish and place it in a basket. Wherever you lose the fish, that is where he will be.'So Musa set out with his young companion, the two of them walking until they reached the rock. Musa lay down to sleep, and the fish stirred in the basket, escaped, and fell into the sea. Allah held back the flow of the water from it like an arch, so that it became a tunnel for the fish."Sufyan said, demonstrating by joining his thumb and index finger and parting them, "Like this."He said, "So they continued on, and when the next day came, Musa said to his young companion, 'Bring us our morning meal. We have certainly suffered fatigue from this journey of ours' [Kahf 18:62]. He had not felt fatigue until he had passed the place he was commanded to reach. 'He said, That is what we were seeking. So they returned, retracing their footsteps' [Kahf 18:64], following their tracks back. The trail of the fish was a wonder for Musa, and a tunnel for the fish."Then he mentioned the rest of the hadith.

حدثنا بهز بن أسد حدثني سفيان بن عيينة إملاء علي عن عمرو

عن سعيد بن جبير قال

قلت لابن عباس قال أبي كتبته عن بهز وابن عيينة حتى أن نوفا يزعم أن موسى ليس بصاحب الخضر قال فقال كذب عدو الله حدثنا أبي بن كعب عن النبي ﷺ قال قام موسى عليه السلام خطيبا في بني إسرائيل فسئل أي الناس أعلم قال أنا فعتب الله عليه إذ لم يرد العلم إليه قال بل عبد لي عند مجمع البحرين هو أعلم منك قال أي رب فكيف لي به قال خذ حوتا فاجعله في مكتل ثم انطلق فحيثما فقدته فهو ثم فانطلق موسى ومعه فتاه يمشيان حتى انتهيا إلى الصخرة فرقد موسى عليه السلام واضطرب الحوت في المكتل فخرج فوقع في البحر فأمسك الله عنه جرية الماء مثل الطاق وكان للحوت سربا وقال سفيان فعقد الإبهام والسبابة وفرج بينهما قال فانطلقا حتى إذا كان من الغد قال موسى لفتاه {آتنا غداءنا لقد لقينا من سفرنا هذا نصبا} قال ولم يجد النصب حتى جاوز حيث أمر {قال ذلك ما كنا نبغ فارتدا على آثارهما قصصا} يقصان آثارهما قال وكان لموسى أثر الحوت عجبا وللحوت سربا فذكر الحديث