Problem of a mosque which is said to have been built on land belonging to the waqf of another mosque
Question

                We have a mosque that was built by one of the charitable foundations on land that was bought from an individual person. The problem here is that some of the elders say that that this land on which the mosque was built is a waqf belonging to another mosque. 

We would like to point out to you the following: 

1.     The person who sold this land to the foundation has documents authenticated by the court.

2.     The people in charge of the mosque to which it is said that this land belongs have not asked for this land up till now, knowing that it has been more than a year since they started building it.

3.     The elders do not have any documents indicating that this land is a waqf belonging to that mosque.

4.     The charitable foundation that built the mosque is prepared to buy the land again if it is proven in court that it is a waqf belonging to this mosque.

5.     The mosque which was built on this land is a jaami’ mosque [mosque in which Friday prayers are held] and there is only one other mosque in this village, which belongs to the Sufis and is filled with innovations and no Jumu’ah prayer is held there.

6.     This mosque – praise be to Allaah – is based on the Sunnah. 
Our question here is: 

What is the ruling on praying in this mosque? What is your opinion on those who warn people against praying in this mosque on the basis that it is built on land concerning which there is some doubt? 

Please advise us, may Allaah reward you with good.
Praise be to Allah.Prayer in the mosque is valid, and no 
    attention should be paid to what some of the elders are saying with no foundation. Based on what you have said, the documents that the person who 
    sold you the land had are proof that the owner of the land does indeed own it, unless something to the contrary can be proven. So the words of 
    some of the elders do not  carry any weight here, especially since those who are in charge of the waqf of that land are present and have not asked 
    for it. 
So carry on praying in the mosque, and do not 
    pay any attention to words that are thrown about with no shar’i proof. Those who warn against praying there should fear Allaah, and not repeat the 
    words of others so long as it is contrary to the facts. They should support their words with shar’i evidence, otherwise it is not permissible for 
    them not to pray in this mosque, let alone warn others and stop them from praying there. 
You say in your question, “The charitable 
    foundation that built the mosque is prepared to buy the land again if it is proven that it is a waqf”. It is not permissible to sell a waqf, but 
    if the mosque to which this land was donated as a waqf has no need of it, it is permissible to sell it to someone who will build a mosque on it, 
    which is what has been done. That is if it is proven that this is a waqf.  
May Allaah help you to do that which pleases 
    Him. We ask Him to accept your righteous deeds. And Allaah knows best.