[Sphericity of the Earth](1)

The answer: The earth is spherical, and this is the view of many of the Muslim scholars and their Imams; and the proof of its being spherical is that the regions of the earth differ, at one and the same time, from night to day, and from morning to evening; and if it were flat, the time would be uniform upon the face of the globe of the earth.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3