Muslim

Hadith Commentary:
1.
There are two forms of constructing a mosque:
➊.
The mosque is built from the very beginning.
➋.
It is expanded or renovated.
In both of the aforementioned cases, the founder will attain the virtue of constructing a mosque.
Allah, the Exalted, will prepare for him a similar palace in Paradise.
Here, a question arises: the reward for other good deeds is tenfold.
But why is the reward for building a mosque only equal or similar to it? The answer is that this similitude does not negate the possibility of more; moreover, equality in the reward of every deed is justice, and any increase in quantity or quality is purely Allah’s grace and bounty.
Hafiz Ibn Hajar rahimahullah has given an excellent answer: in the reward for building a mosque, only one house will be granted in Paradise, but in quality, it will be far superior to any house in this world.
Sometimes, even in this world, one house is more magnificent and splendid than a hundred other houses.
Imam Nawawi rahimahullah said:
It is possible that the excellence of this house in Paradise will be over the other houses of Paradise just as the excellence of a mosque in this world is over the rest of the houses.
In any case, the house granted in Paradise will be very spacious and excellent, and by “similarity” is not meant equality in every aspect; moreover, there is a clear indication in this that the founder will be admitted to Paradise, because the purpose of building a house is to reside in it, and residence will only be after entering Paradise.
(Fath al-Bari: 1/706)
2.
Multiple objections were raised against Uthman radi Allahu anhu regarding the expansion of the Prophet’s Mosque, such as:
If the current form of the mosque were better, then the Messenger of Allah sallallahu alayhi wa sallam and his companions would have been more deserving of it.
The said expansion is being carried out from the public treasury (Bayt al-Mal) without the permission of the Muslims, which is not correct.
This work is not for the pleasure of Allah, but merely for fame and ostentation.
Uthman radi Allahu anhu answered all these objections with a single hadith of the Prophet’s Mosque:
➊.
I have done this with the permission of the Messenger of Allah sallallahu alayhi wa sallam, because his statement is that if anyone builds a mosque for the sake of Allah, Allah will grant him a house like it in Paradise.
It is thus clear that to receive a similar reward in Paradise, building a mosque is permissible.
➋.
In this hadith, the glad tidings of a house in Paradise are given to the one who builds it himself.
I am also doing this for the attainment of Paradise.
Therefore, the question of constructing the mosque from the public treasury does not arise.
Previously, I had also purchased a plot of land for the mosque.
➌.
In this narration, it is stated that whoever builds a mosque seeking Allah’s pleasure, he will be granted its like in Paradise.
I am doing this very work for this great purpose.
Therefore, you have no right to attack my intention; you do not know what is in my heart.
In short, Uthman radi Allahu anhu gave a comprehensive answer to all objections from a single hadith.
Imam Ibn al-Jawzi rahimahullah has written that whoever builds a mosque and has his name inscribed on it is not sincere, but rather is accustomed to ostentation and showing off, because the glad tidings of reward given in the hadith have sincerity for Allah as a fundamental condition.
If someone builds a mosque in exchange for wages, he will not be entitled to the glad tidings mentioned, although apart from the glad tidings given in the hadith, he will not be deprived of reward.
It is mentioned in the hadith that three people will enter Paradise because of an arrow:
The maker, the one who uses it, and the one who provides the means for it.
In this, it is not clarified regarding the maker whether he made it for wages or made it for the sake of Allah and handed it over to a warrior.
Similarly, if a person designates a piece of his owned land as a mosque, and then people perform prayers there without constructing a building, or if someone designates a ready-made building as a mosque, will he also attain the aforementioned virtue or not? According to the apparent wording, he will not be entitled to this virtue, because there was no construction of a mosque in it, but if the objective is considered, then such a person will also not be deprived of the mentioned reward.
Likewise, by “building” is meant both the one who constructs himself and the one who orders the construction, and both are entitled to the glad tidings mentioned.
(Fath al-Bari: 1/706)

Hadith Commentary: Benefits and Issues:

During the Prophetic era (sallallahu alayhi wa sallam), his mosque was extremely simple: the walls were built from unbaked bricks, with a roof made of palm branches, and its pillars were of palm wood. When Uthman (radi Allahu anhu) expanded it, he changed this material. The walls were constructed from hewn stones, plastered with lime, and the pillars were also made from hewn stones, while the roof was made from high-quality teak wood.

The noble Companions (radi Allahu anhum ajma'in) objected to the excellence and change of materials, as they believed that the mosque should be constructed simply, as it was in the earlier era. However, Uthman (radi Allahu anhu), considering the newly constructed houses, used superior and excellent materials and said:

I have made it so superior, excellent, and beautiful so that Allah will grant me, on the Day of Resurrection, a superior and excellent house in accordance with my taste and longing.

Hadith Commentary: Benefits and Issues: "Mithlahu" (like it) does not mean of the same size and measurement, or of the same kind of material; rather, what is meant is: with the same good intention and excellence with which he builds, in that way he will receive a superior and excellent house in Paradise. For there is no parallel or example of Paradise in this world, nor can there be.

1:
This similarity will be in terms of quantity; in terms of quality, this house will be far superior to that one.

Commentary:
(1)
To build a mosque for Allah means that this act should be done with sincerity.
No deed is accepted without sincerity.