A few pages later we read the following:رَبَّنَا وَابْعَثْ فِيهِمْ رَسُولًا مِنْهُمْ يَتْلُو عَلَيْهِمْ آَيَاتِكَ وَيُعَلِّمُهُمُ الْكِتَابَ وَالْحِكْمَةَ وَيُزَكِّيهِمْ إِنَّكَ أَنْتَ الْعَزِيزُ الْحَكِيمُOur Lord, please raise up among them a prophet who recites Your verses upon them, who teaches them the Book, and teaches them wisdom, and who purifies them. Truly You are the Mightiest, the Most Wise.
If you read the Arabic, you will see that verse 129 and verse 151 mirror each other's wording (it's apparent in the English translation too). This is Allah's way of telling us that the sending of Prophet Muhammad is Allah's answer to Prophet Ibraheem and his son's prayer.فَلَا تَخْشَوْهُمْ وَاخْشَوْنِي وَلِأُتِمَّ نِعْمَتِي عَلَيْكُمْ وَلَعَلَّكُمْ تَهْتَدُونَ (150) كَمَا أَرْسَلْنَا فِيكُمْ رَسُولًا مِنْكُمْ يَتْلُو عَلَيْكُمْ آَيَاتِنَا وَيُزَكِّيكُمْ وَيُعَلِّمُكُمُ الْكِتَابَ وَالْحِكْمَةَ وَيُعَلِّمُكُمْ مَا لَمْ تَكُونُوا تَعْلَمُونَ (151) فَاذْكُرُونِي أَذْكُرْكُمْ وَاشْكُرُوا لِي وَلَا تَكْفُرُونِ (152)150. So don't fear them, and fear Me, that I may perfect My favor on you, and that you may be guided.
151. Just as We have sent you a prophet of your own who recites upon you Our verses, who purifies you, who teaches you the Book and wisdom, and who teaches you what you did not know before.
152. So remember Me, and I will remember you, and be thankful toward Me and never ungrateful.
This little Quranic story can be considered Islam's 'back story'; the two prophets who built the Ka'ba made a prayer to Allah, Allah's answer, which came about 2500 years later, was Prophet Muhammad, a descendant of the two prophets, and today all of us Muslims are living the consequences of this story.