Abu Dawud

Benefits and Issues:
To sit directly on top of the grave or to become its attendant in the expression of grief is prohibited (haram).
Similarly, to solidify it (make it permanent with construction) or to build a dome or the like over it is prohibited (haram).
There is no harm in sitting near the grave out of necessity.
(See Hadith 3212)

(1) "Construction" means raising the grave like a building or constructing a structure around the grave, whether it is for the protection of the grave or for the convenience of visitors; in any case, it is prohibited because in this way the grave will remain for a long time. It will cause inconvenience to those who come later, and it also becomes a cause for grave worship. Nowadays, such graves have become dens for criminals and addicts.

(2) "Addition" means adding soil other than the soil that comes out of the grave itself, which is prohibited because in this way the grave will be raised above the prescribed Shariah limit and it will take longer to disappear. Or it may mean making the grave unnecessarily long and wide, which is also prohibited because it will cause a shortage of space and create difficulties for others, and also waste space without purpose.

(3) Tahsis, that is, making the grave solid with lime or similar materials, because this gives it strength and durability, whereas the intent of the Shariah is that the grave should remain for a short time and then disappear so that space is left for those who come later. Some scholars have permitted plastering the grave with soil, but from this hadith it is understood that this soil should not be other than the soil of the grave itself; rather, water should be poured over the grave's soil and smoothed by hand. However, if a grave collapses and a pit is formed, then it can be filled with separate soil because this is a necessity.

(4) "Writing," for example: name, lineage, address, date of death, verses of the Qur'an, hadiths, etc.—in short, writing anything is prohibited because this will cause the grave to remain for a long time. Writing the Qur'an, etc., is also prohibited because graves are subject to decay and this will result in disrespect to the sacred words. Moreover, the relatives already know the grave without any inscription, and the general public gains no benefit from such an announcement, so writing is pointless and, in fact, ostentation.

(5) The prevalence of something among the general public is not proof of its permissibility when it is in clear contradiction to the explicit command of the Messenger sallallahu alayhi wa sallam, such as the aforementioned matters. After all, shirk (polytheism) has always been popular among the masses in every era.

Urdu marginal note:
“He forbade sitting [on the grave]” because in this there is disrespect to the occupant of the grave, or it is to prevent sitting as a form of mourning, or it means sitting as a caretaker (mujawir) at the grave. Some have interpreted this as referring to sitting for the purpose of relieving oneself. The correct view is that all of the above-mentioned forms are prohibited. Similarly, leaning against the grave is also prohibited because in this too there is disrespect to the occupant of the grave.

In that era, the function that was fulfilled by lime is, in present times, fulfilled by cement; therefore, the use of cement on graves is also prohibited. (For further details, see Hadith: 2029)

Hadith Commentary: Benefits and Issues: ➊
Allamah Turpushti Hanafi rahimahullah has written:
That to make a grave solid (with construction) or to pitch a tent over it—both are prohibited,
because there is no benefit in them and this was the practice and custom of the people of ignorance (Jahiliyyah).
Abdullah bin Umar radi Allahu anhuma saw a tent pitched over the grave of Abdur Rahman bin Abi Bakr radi Allahu anhuma, so he said,
“O servant! Remove this,”
for the deeds of the deceased themselves provide shade for him. And some of the Hanafis have also said that this is a waste of wealth.
And Imam Shafi’i rahimahullah says,
“I saw the Imams of Makkah ordering the demolition of such structures.”
Therefore, to say:
From the beginning until now, domes have been built over the shrines of the pious and scholars of the Ummah,
so (the permissibility of building domes is established by the practical consensus of the Ummah)
is contrary to reality.
And the claim of consensus (ijma‘) is incorrect.
Moreover, any consensus that is contrary to the text (nass) is not acceptable, nor is consensus against the text possible.
Similarly, Ibn Abidin has claimed a practical consensus (ijma‘ ‘amali) on the permissibility of writing on graves.
Whereas Imam Abi rahimahullah has written that the Imams of the Muslims did not give a fatwa of permissibility, nor did they make a bequest to have writing on their graves.
Rather, the majority of them gave a fatwa of impermissibility and wrote the same in their works.
(Fath al-Mulhim 2/507)
Therefore, this is the wrong practice of people and cannot be called consensus.
If now the practice of usury is widespread among all the Muslims of the world, will it become permissible?
Moreover, these gentlemen made this claim for the graves of scholars and the pious,
but now this epidemic has become widespread.
So, should a fatwa of permissibility be given by calling this a practical consensus?
Whereas the real situation is that in every era and every time, there have been and still are such people among the Imams of the Muslims who continue to prohibit these wrong actions.
The same is the case with spreading cloths or offering flowers at these shrines,
now people call upon those in the graves, making vows or offerings for the fulfillment of their needs and the removal of their difficulties.
And this action is, by consensus, invalid.
(Sharh Sahih Muslim Saeedi 2/817)
So, should this action now be declared permissible
just because everyone is doing it?

➋
Just as making a grave solid and constructing a building over it is impermissible,
similarly, it is not correct to sit as a caretaker (mujawir) over it.
Imam Nawawi rahimahullah has written that making a grave solid,
constructing a building over it, and sitting (upon it) are all prohibited.

Explanation:
1:
One reason for this prohibition is that it constitutes extravagance, as it brings no benefit to the deceased. Secondly, it involves such veneration of the dead that it can lead a person to shirk (associating partners with Allah).

2:
This prohibition is absolute; it includes writing the name of the deceased, the date of death, verses of the Qur’an for blessing, the Beautiful Names (Asma’ al-Husna), etc.—all are encompassed within it.

3:
For example, domes and the like.

4:
This prohibition is due to the respect and honor of the deceased; such actions result in the humiliation and disrespect of the deceased, and thus they have been forbidden.

Benefit:
Applying lime or gypsum was a method in previous times to strengthen a structure; nowadays, cement is used for this purpose.
It is sufficient to cover the grave only with the soil that was taken out from the grave itself.
Adding more soil or reinforcing the grave is prohibited.
In this regard, constructing a room, dome, etc., over the grave will be even more strictly prohibited.