Tafsir Ibn Abbas: Al-Kahf, Ayah 65

So there they found one of Our servants namely al-Khidr to whom We had given mercy from Us — according to one opinion this mercy was prophethood; according to another it was authority and this latter is the opinion of the majority of scholars — and We had taught him knowledge from Us ‘ilman is the second direct object in other words some knowledge of unseen things; al-Bukhārī reports the following hadīth ‘Moses was delivering a sermon among the Children of Israel and was asked “Who is the most knowledgeable of people?” to which he Moses said “Myself”. God then reproached him for not having attributed his knowledge as coming from Him. God then revealed to him the following “Truly there is a servant of Mine at the juncture of the two seas; he is more knowledgeable than you”. Moses then asked “My Lord how do I reach him?” He God said ‘Take a fish with you and place it in a basket and the place where you lose the fish will be the place where he is.” He Moses took a fish and placed it in a basket and departed together with his lad Joshua son of Nun until they reached the rock. There they placed their heads back and fell asleep. The fish began to move about in the basket until it escaped from it and fell into the sea and it made its way into the sea in an amazing manner. God then held back the flow of the water preventing it from engulfing the fish forming a kind of arch over it. When he awoke his companion Joshua forgot to inform him of what had happened to the fish and so they journeyed on for the remainder of that day and night until on the morning of the second day Moses said to his lad ‘Bring us our breakfast’ to where he says and it made its way into the sea in an amazing manner’. He Bukhārī said ‘For the fish it the way into the sea was by ‘burrowing’ saraban and for Moses and his lad it this way was ‘amazing’ ‘ajaban …’ and so on to the end of Bukhārī’s report.