This is from Wikipedia, not the best source in the world, nevertheless:
One influential modern Muslim jurist has been said to have claimed that the earth is flat, and that anyone who denies this is an unbeliever. Ibn Baz, the Grand Mufti of Saudi Arabia, was a traditionally educated cleric who suffered from blindness. In 1993, he is said to have issued a fatwa, or religious ruling, declaring, "The Earth is flat. Whoever claims it is round is an atheist deserving of punishment."[42]Youssef M. Ibrahim, "Muslim Edicts Take on New Force", New York Times, February 12, 1995.
While the edict reportedly caused embarrassment for many Saudis, Ibn Baz issued a statement maintaining that the earth was spherical but expansive enough to be flat(Audio recording of Ibn Baz - Binbaz.org. Translation provided below)
Shaykh Bin Baz on the Roundness of the Earth (with Sound) on the Shaykhs website
The audio is played automatically as the page is opened:
http://binbaz.org.sa/RecDisplay.asp?f=n-04-1407-0300007.htm
translated...
-The question and answer was translated by Aqeel Walker, a former translator for Darussalam Publications in Riyadh, Saudi Arabia:
Introduction: The following letter reached the program (broadcast program) from Kenya, sent by our brother, the student, Ibraheem Muhammad Al-Awwal. The brother says, "I heard the program Nurun 'alad-Darb (A Light upon the Path) and I benefited greatly from it. Therefore, I wanted to send these questions to you all because their topics are very perplexing to me. The first is: Is the earth round or flat?"
Shaikh Bin Baz: According to the people knowledge (scholars of Islaam) the earth is round, for indeed Ibn Hazim and a group of other scholars mentioned that there is a consensus (unanimous agreement, Ijmaa') among the people of knowledge that it is round. This means that all of it is connected together thus making the form of the entire planet like a ball. However, Allaah has spread out surface for us and He has placed firm mountains upon it and placed the animals and the seas upon it as a mercy for us. For this reason, Allaah said: "And (do they not look) at the Earth, how it was made FLAT (Sutihat)." [Al-Ghaashiyyah (88):20]
Therefore, it (the Earth) has been made flat for us in regards to its surface, so that people can live on it and so that people can be comfortable upon it. The fact that it is round does not prevent that its surface has been made flat. This is because something that is round and very large, if it is made flat (its surface), then its surface will become very vast or broad (i.e. having a flat appearance). Yes."
i dont trust personally this translation. it would be better if anybody could hear that audio and translate it here.
sheikh Baz strongly denied that claim, describing the allegation as a "pure lie" and saying that he only denied Earth's rotation. [21] [22]
Supporters of Ibn Baz said that the book in which the flat earth claim was supposed to have been laid out does not exist, and that the entire controversy was based on one interview with Egyptian journalists. They said that Ibn Baz, as he clarified later, was referring to the surface of earth that we walk on being flat although he believed the Earth to be spherical