Tafsir of Ta-Ha 20:106

فيذرها

Then He shall leave it, referring to the earth;

قاعا صفصفا

as a level smooth plain. This means one expanse spread out. The word Qa` means a piece of land that is level and the word Safsafa is used to place emphasis on this meaning. It has also been said that Safsafa means that which has no vegetation growing in it. The first meaning is preferred, even though the second meaning is also included by necessity. In reference to this, Allah says,

ﻻ ترى فيها عوجا وﻻ أمتا