It is disliked to build over it (i.e., graves) according to Imam Ahmed and his companions, whether adhesive type or not. The author of (Kitab) al-Mustau’ab (i.e. Imam Muhammed ibn ‘Abdallah as-Samuri al-Hanbali) and al-Muharrar (i.e. Imam Majd ad Din Ibn Taymiyya al-Hanbali (d. 653), the grand father of Ibn Taymiyya) said: There is no harm if there is a dome or a house or similar building at the site in his possession. This is due to the fact that permission has been granted to be buried in such a place. The author of al-Muharrar said: and disliked in public graveyards (or shared graveyards) as it narrows the space and resembles worldly buildings. And said in al-Mustau’ab: and disliked if in public graveyards ……In al-wasila (it is said): “It is disliked to build pompous domes”, from which it is apparent: there is no objection to a building enclosing it [the tomb](bina mulasiq) because its intention is to mark and preserve it.” Abu Hafs prohibited a room/chamber, he said: It is to be destroyed, it is prohibited to pitch a fustat, Imam Ahmed disliked to pitch a tent and fustat, and Ibn Umar ordered the removal of it and said: “his deeds shade him”. The apparent of their words does not prohibit construction …it only prohibits bragging and showing off, and this is view of the Malikis, Ibn Tamim and others said: It prohibits building over that which is made waqf for the public, and this is similar what the Shafis and others said, (Imam Shafi) said: “I saw the Imams/governors of Mecca ordering the demolition of what was built” , and this is similar in meaning to what Ibn Tamim and others said…..(…)….And it is said in al-Fusul: The dome and the hangar and the turbah, (built on land) which was in his possession he can do what he wants, but it is disliked in land which is for the public, because it narrows it…..
This should not be considered as an isolated opinion, as some might try to brush it off. The Imam wasn’t just constructing his own opinion but directly quoting from the books of early hanbali scholars. Neither was the Imam unaware of Ibn Taymiyya that some pseudo-salafis might imagine the Imam was unfortunate in not receiving the light of Ibn Taymiyya and Ibn al Qayyim.
The opinion of Shams ad-din Ibn Muflih, was also said by the hanbali scholar Burhan ad-Din Ibn Muflih (d. 884H) in his “Sharh Mughni” :
390 – حَدثنَا صَالح قَالَ حَدثنِي أبي قَالَ حَدثنَا يحيى بن سليم عَن عبد الله بن عُثْمَان عَن عبد الرحمن بن سابط عَن عبد الله بن ضَمرَة السَّلُولي قَالَ مَا بَين الْمقَام إِلَى الرُّكْن إِلَى زَمْزَم إِلَى الْحجر قبر تِسْعَة وَتِسْعين نَبيا جَاءُوا حاجين فقبروا هُنَالك
Between the maqam and al-hijr are the graves of 99 Prophets
(After mentioning the chain of report) said: between Maqaam and Rukn, and towards Zamzam and Hajr (i.e. in Masjid al-Haram) are graves of 99 prophets. They had come for pilgrimage and had died there.
and also Ibn Sa’ad (d. 230H) in his Tabaqat (1:25) said:
“When Ismail (عليه السلام) was 20 years of age, his mother Hajara (عليه السلام) died. She was ninety years of age. Ismail (a.s.) died after the death of his father. He was buried in Hajr near his mother Hajara (عليه السلام). Beyond this is the Holy Kaaba.” and later says, “The grave of Ismail (عليه السلام) is below the ‘Mizaab’ between ‘Rukn’ and ‘Bayt’.”
 This is understood if one knows the full statement of Imam al-Shafi (d. 204H):
I have seen the governors who demolished[tombs] in Mecca built inside the city, and I found no jurist who saw therein a wrong decision. If it was a question of tombs on land owned by the dead in their lifetime or bequeathed to their offspring, nothing that was built on their part was destroyed.Only that which no one called his own was demolished.The demolition took place so that the space around the tomb would not be inaccessible to[other] people or prevent others from being buried there, and to avoid people’s being hampered.” [al-Umm 1:277]
As one can read, Imam Shafi is mentioning that only that which is built on public graveyards were destroyed and this was because it narrows the space there, and that this does not apply to what was built on private land. And this is why Ibn Muflih said that the opinion of Shafis is similar to what Ibn Tamim and others said that the prohibition only applies to land which is made waqf for the public. The Wahhabis partially quote what Imam Shafi said to propagate a false meaning of it. So here we are having a senior Hanbali scholar refuting Wahhabis even on this false attribution upon the Shafi madhab.