18:77
فَٱنطَلَقَا حَتَّىٰٓ إِذَآ أَتَيَآ أَهْلَ قَرْيَةٍ ٱسْتَطْعَمَآ أَهْلَهَا فَأَبَوْا۟ أَن يُضَيِّفُوهُمَا فَوَجَدَا فِيهَا جِدَارًا يُرِيدُ أَن يَنقَضَّ فَأَقَامَهُۥ ۖ قَالَ لَوْ شِئْتَ لَتَّخَذْتَ عَلَيْهِ أَجْرًا
So they set out, until when they came to the people of a town, they asked its people for food, but they refused to offer them hospitality. And they found therein a wall about to collapse, so al-Khidh r restored it. [Moses] said, "If you wished, you could have taken for it a payment."
Context in Surah Al-Kahf
Nearby ayahs help place verse 18:77 in sequence and meaning.
۞ قَالَ أَلَمْ أَقُل لَّكَ إِنَّكَ لَن تَسْتَطِيعَ مَعِىَ صَبْرًا
[Al-Khidh r] said, "Did I not tell you that with me you would never be able to have patience?"
قَالَ إِن سَأَلْتُكَ عَن شَىْءٍۭ بَعْدَهَا فَلَا تُصَـٰحِبْنِى ۖ قَدْ بَلَغْتَ مِن لَّدُنِّى عُذْرًا
[Moses] said, "If I should ask you about anything after this, then do not keep me as a companion. You have obtained from me an excuse."
قَالَ هَـٰذَا فِرَاقُ بَيْنِى وَبَيْنِكَ ۚ سَأُنَبِّئُكَ بِتَأْوِيلِ مَا لَمْ تَسْتَطِع عَّلَيْهِ صَبْرًا
[Al-Khidh r] said, "This is parting between me and you. I will inform you of the interpretation of that about which you could not have patience.
أَمَّا ٱلسَّفِينَةُ فَكَانَتْ لِمَسَـٰكِينَ يَعْمَلُونَ فِى ٱلْبَحْرِ فَأَرَدتُّ أَنْ أَعِيبَهَا وَكَانَ وَرَآءَهُم مَّلِكٌ يَأْخُذُ كُلَّ سَفِينَةٍ غَصْبًا
As for the ship, it belonged to poor people working at sea. So I intended to cause defect in it as there was after them a king who seized every [good] ship by force.