It is narrated from Hazrat Ibn Abbas (may Allah be pleased with them both) that once he and Har bin Qais Fazari had a difference of opinion regarding the companion of Hazrat Musa (peace be upon him) to whom he traveled and requested in the court of Allah to meet. Hazrat Ibn Abbas (may Allah be pleased with them both) was of the opinion that he was Hazrat Khidr (peace be upon him). Meanwhile, Hazrat Ubayy bin Ka'b (may Allah be pleased with him) passed by. Hazrat Ibn Abbas (may Allah be pleased with them both) called out to him and said, "My companion and I have differed regarding the person to whom Hazrat Musa (peace be upon him) traveled and requested to meet. Have you heard anything from the Prophet (peace and blessings be upon him) regarding this?" He replied, "Yes, I heard the Prophet (peace and blessings be upon him) say: Once Hazrat Musa (peace be upon him) was addressing a gathering of Bani Israel when a man stood up and asked him, 'Is there anyone more knowledgeable than you in your deeds?' Hazrat Musa (peace be upon him) replied, 'No.' Upon this, Allah Almighty revealed that 'Our servant Khidr is more knowledgeable than you.' Hazrat Musa (peace be upon him) asked the way to meet him, so Allah Almighty made a fish a sign for him and said, 'When you do not find the fish, return, for there you will meet him.' Hazrat Musa (peace be upon him) set out on the journey, and at one place they stopped and he said to his servant, 'Bring our breakfast, for we have faced much hardship in this journey.' There Hazrat Musa (peace be upon him) found the fish missing, so both of them returned following their footsteps, and then the incident occurred as Allah Almighty has mentioned in His Book."