Early Muslim Consensus: The Earth is Round
Ibn Taymiyyah (d. 728 H / 1328 CE), may Allah be merciful with him, in his famous treatise, ar-Risalah al-'Arshiyah, refutes the position of the neo-Platonic philosophers who identified Allah's Throne with the ninth celestial sphere (Majmu'ul-Fatawa, Vol. 6, pp.546 -ff). In the course of his response, Ibn Taymiyah discusses the question of the earth is it round or flat? He writes:
[That] celestial bodies are round (istidaaratul-aflaak) - as it is the statement of astronomers and mathematicians (ahlul-hay'ah wal-hisab) - it is [likewise] the statement of the scholars of the Muslims; as Abul-Hasan ibn al-Manaadi, Abu Muhammad ibn Hazm, Abul-Faraj ibn al-Jawzi and others have quoted: that the Muslim scholars are in agreement [that all celestial bodies are round]. Indeed Allah - taala - has said: And He (i.e., Allah) it is Who created the night and the day, the sun and the moon. They float, each in a falak. Ibn Abbas says: A falaka like that of a spinning wheel.
Ibn Taymiyah continues: The [word] falak [in the Arabic language] means that which is round. From which is the statement [of the Arabs]: <> (Vol.6 , pp. 566-567)
In an earlier passage (Vol.6 , pp.565 -566), Ibn Taymiyah discusses why those on the other side of the earth are not below us, just like we are not below them. He writes:
As for the other side of the earth it is surrounded by water. [Note: Admittedly, Ibn Taymiyah - as all Muslim scholars of his day- were not aware of the Americas and believed that the Old World was encompassed by an ocean.] There are no human beings or anything like that [on that side]. Even if we were to imagine that people were on that side of the earth, such individuals would still be on the face of the earth. Those on that side of the earth are not below those who are on this side; just like those on this side are not below those on that side. For as all spherical bodies surround a center point (markaz), no one side of a spherical body is under the other, nor is the north pole under the south [Note: Unlike Western maps, Muslim cartographers (map-makers) would draw the world with the south-side up.] or vice versa.
In another passage (Vol.5 , p.150 ) Ibn Taymiyah clearly states the earth is spherical.
Significantly Abu Ya'la in his work Tabaqatal-Hanabilah (Biographical Entries of the Hanabali Scholars) quotes the unanimous consensus (ijma) of all Muslim scholars that the earth is round.
This consensus was mentioned by the scholars of the second generation (the students of the Prophet's Companions) and was based upon Ibn Abbas' explanation to21 :33 (previously cited) and other evidences.
The later belief of Muslim scholars, like as-Suyuti (died 911 AH / 1505 CE) that the earth is flat represents a deviation from this earlier opinion.