The Sahabah (may Allah be pleased with them) differed concerning some issues of knowledge, according to what each of them knew, whilst paying attention to proper etiquette, each of them showing due respect to others and appreciating their brothers’ knowledge. One example of this is when the two Companions, ‘Abdullah ibn ‘Abbas and al-Hurr ibn Qays (may Allah be pleased with them both) disagreed concerning the companion of Musa (peace be upon him) who is mentioned in the verse {And they found a servant from among Our servants to whom we had given mercy from us and had taught him from Us a [certain] knowledge. Moses said to him, “May I follow you on [the condition] that you teach me from what you have been taught of sound judgement?”} [al-Kahf 18:65-66]. The view of Ibn ‘Abbas (may Allah be pleased with him) was that this was al-Khadir, and this was the view in which Ubayy ibn Ka‘b supported him, based on what he had heard from the Prophet (blessings and peace of Allah be upon him) about the story of Musa and al-Khadir (peace be upon them both). So he told him that he had heard the Prophet (blessings and peace of Allah be upon him) saying that when Allah’s Prophet Musa was with a group of Israelites, a man came to him and asked him: Do you know of anyone more knowledgeable than you on earth? Based on his own opinion, Musa denied that there was anyone more knowledgeable than him, because he was a Prophet who received revelation. But Allah rebuked him for not referring the matter to Him, as is narrated in Sahih Muslim. It was said that this was a rebuke to Musa (peace be upon him) and a lesson for those who came after him, so that no one else would follow him in praising himself and being filled with self-admiration, and thus be doomed. Allah (may He be glorified and exalted) revealed to him: There is someone who is more knowledgeable than you, to whom Allah has given knowledge other than that which He revealed to you. He is a person whose name is Khadir. So Musa asked: How can I meet him? Allah made the fish a sign for him, to show him where al-Khadir was, so that he could meet him. It was said to him: When you lose the fish on the seashore, then retrace your steps, for you will meet him. That was when Musa asked how he could meet al-Khadir. Allah (may He be exalted) said: Look for him on the shore, near the rock. He said: O Lord, how can I reach him? He said: Take a fish in a basket, and where you lose it, he will be there. It was said that he took a salted fish, and said to his servant: When you lose the fish, tell me. The phrase “And he was following the path of the fish in the sea” means: he was looking at it whilst he was on the shore, walking alongside it, until he reached al-Khadir. It does not mean that he was literally following its path in the sea. And it was said that Musa met al-Khadir on an island in the sea, and to reach that island one must travel by sea. And it was said that the pronoun in the phrase “he was following” refers to the servant of Musa, Yusha‘ ibn Nun. That was because Musa (peace be upon him) had said to him: When you lose the fish, tell me, because it was the sign of where he would meet al-Khadir. The servant said to Musa, as Allah (may He be exalted) tells us: {Did you see when we retired to the rock? Indeed, I forgot [there] the fish. And none made me forget it except Satan - that I should mention it} [al-Kahf 18:63]. After they had rested beside the sea, the servant forgot the fish, then they travelled on for a while. When the servant remembered that, he told Musa (peace be upon him) about it, and Musa said to him: {“That is what we were seeking.” So they returned, following their footprints} [al-Kahf 18:64]. So they retraced their steps until they reached the place where they had lost the fish, and there they found Khadir, after which there happened the events of which Allah (may He be glorified and exalted) tells us in His Book, in Surat al-Kahf. After that, it became clear to Musa how great al-Khadir’s knowledge was, which was based on what Allah had taught him of the unseen, and the events that took place by Allah’s decree, which none of the Prophets knew except what they were taught about by the Creator (may He be glorified and exalted). In this hadith, we see that one should put up with some hardship for the sake of seeking knowledge and learning more, and acknowledge the status of the one who is more knowledgeable. We also see that disagreeing about some issues of knowledge, if each person is seeking to learn the truth without being stubborn, is something permissible. This hadith also indicates that in the event of disagreement, we should refer to people of knowledge, and that it is essential to show humility towards knowledge and people of knowledge. It also indicates that one should take provisions when travelling. And it indicates that the knowledgeable person should not become too proud of his knowledge..