In this Ayah there is a proof that the word Qaryah (village) may be used to refer to a city (Madinah), because Allah first says,
حَتَّى إِذَآ أَتَيَآ أَهْلَ قَرْيَةٍ
(till when they came to the people of a town (Qaryah)) 18:77, but here He says:
فَكَانَ لِغُلَـمَيْنِ يَتِيمَيْنِ فِى الْمَدِينَةِ
(it belonged to two orphan boys in the town (Al-Madinah);) This is like the Ayat:
وَكَأَيِّن مِّن قَرْيَةٍ هِىَ أَشَدُّ قُوَّةً مِّن قَرْيَتِكَ الَّتِى أَخْرَجَتْكَ
(And many a town (Qaryah), stronger than your town which has driven you out We have destroyed) 47:13 and;
وَقَالُواْ لَوْلاَ نُزِّلَ هَـذَا الْقُرْءَانُ عَلَى رَجُلٍ مِّنَ الْقَرْيَتَيْنِ عَظِيمٍ
(And they say: "Why is not this Qur'an sent down to some great man of the two towns (Al-Qaryatayn)")43:31 meaning Makkah and At-Ta'if. The meaning of the Ayah 18:82 is: "I repaired this wall because it belonged to two orphan boys in the city, and underneath it was some treasure belonging to them." `Ikrimah, Qatadah and others said, "Underneath it there was some wealth that was buried for them." This meaning is apparent from the context of the Ayah, and is the view chosen by Ibn Jarir (may Allah have mercy on him).
وَكَانَ أَبُوهُمَا صَـلِحاً
(their father was a righteous man,) indicates that a righteous person's offspring will be taken care of, and that the blessing of his worship will extend to them in this world and in the Hereafter. This will occur through his intercession for them, as well as their status being raised to the highest levels of Paradise, so that he may find joy in them. This was stated in the Qur'an and reported in the Sunnah. Sa`id bin Jubayr narrated from Ibn `Abbas: "They were taken care of because their father was a righteous man, although it is not stated that they themselves were righteous."
فَأَرَادَ رَبُّكَ أَن يَبْلُغَآ أَشُدَّهُمَا وَيَسْتَخْرِجَا كَنزَهُمَا
(your Lord intended that they should attain their age of full strength and take out their treasure) Here will is attributed to Allah, the Exalted, because no one else is able to bring them to the age of full strength and puberty except Allah. In contrast, He said about the boy:
فَأَرَدْنَآ أَن يُبْدِلَهُمَا رَبُّهُمَا خَيْراً مِّنْهُ زَكَـوةً
(So we intended that their Lord should exchange him for them for one better in righteousness) and concerning the ship:
فَأَرَدتُّ أَنْ أَعِيبَهَا
(So I wished to make a defective damage in it,) And Allah knows best.
رَحْمَةً مِّن رَّبِّكَ وَمَا فَعَلْتُهُ عَنْ أَمْرِى
(as a mercy from your Lord. And I did them not of my own accord.) Meaning, `These three things that I did, come from the mercy of Allah for those we have mentioned, the crew of the ship, the parents of the boy and the two sons of the righteous man; I was only commanded to do these things that were enjoined upon me.' This is proof and evidence in support of those who say that Al-Khidr, peace be upon him, was a Prophet, along with the Ayah which we have already quoted:
فَوَجَدَا عَبْدًا مِّنْ عِبَادِنَآ ءَاتَيْنَاهُ رَحْمَةً مِّنْ عِندِنَا وَعَلَّمْنَاهُ مِن لَّدُنَّا عِلْمًا
(Then they found one of Our servants, on whom We had bestowed mercy from Us, and whom We had taught knowledge from Us.) 18:65
Imam Ahmad recorded that Abu Hurayrah, may Allah be pleased with him, said that the Prophet said concerning Al-Khidr؛
«إِنَّمَا سُمِّيَ خَضِرًا لِأَنَّهُ جَلَسَ عَلَى فَرْوَةٍ بَيْضَاءَ، فَإِذَا هِيَ تَهْتَزُّ مِنْ تَحْتِهِ خَضْرَاء»
(He was called Al-Khidr because he sat on a barren Farwah that turned white, then it turned green (Khadra') beneath him.) Imam Ahmad also recorded this from `Abdur-Razzaq. It was also recorded in Sahih Al-Bukhari from Hammam from Abu Hurayrah that the Messenger of Allah ﷺ said,
«إِنَّمَا سُمِّي الْخَضِرَ لِأَنَّهُ جَلَسَ عَلَى فَرْوَةٍ، فَإِذَا هِيَ تَهْتَزُّ مِنْ تَحْتِهِ خَضْرَاء»
(He was called Al-Khidr because he sat on a barren Farwah and it turned green (Khadra') beneath him.) The meaning of Farwah here is a patch of withered vegetation. This was the view of `Abdur-Razzaq. It was also said that it means the face of the earth.
ذَلِكَ تَأْوِيلُ مَا لَمْ تَسْطِـع عَّلَيْهِ صَبْراً
(That is the interpretation of those (things) over which you could not be patient.) meaning, `this is the explanation of the things which you could not put up with or be patient with until I took the initiative of explaining them to you.' When he explained them and made them clear and solved the confusion, he used a milder form of the verb,
تَسْطِـع
(you could) When the matter was still confusing and very difficult, a more intensive form was used,
سَأُنَبِّئُكَ بِتَأْوِيلِ مَا لَمْ تَسْتَطِع عَّلَيْهِ صَبْراً
(I will tell you the interpretation of (those) things over which you were unable to be patient with) 18:78. The intensity of the verbal form used reflects the intensity of the confusion felt. This is like the Ayah:
فَمَا اسْطَـعُواْ أَن يَظْهَرُوهُ
(So they (Ya`juj and Ma`juj) were not able to scale it) 18:97 which means ascending to its highest point,
وَمَا اسْتَطَـعُواْ لَهُ نَقْبًا
(nor are they able to dig through it) 18:97 which is more difficult than the former. The intensity of the verbal form used reflects the difficulty of the action, which has to do with the subtleties of meaning. And Allah knows best. If one were to ask, what happened to the boy-servant of Musa who appears at the beginning of the story but then is not mentioned The answer is that the objective of the story is what happened between Musa and Al-Khidr. Musa's boy-servant was with him, following him. It is clearly mentioned in the Sahih Hadiths referred to above that he was Yusha` bin Nun, who was the one who became the leader of the Children of Israel after Musa, peace be upon him.