(In Surah Ar-Rahman, the word) «صلصال» means such clay in which sand is mixed, and it sounds like baked clay when struck. Some have said that the meaning of «صلصال» is «منتن‏.‏» , that is, foul-smelling. Originally, this word is derived from «صل‏» . The letter "fa" is repeated, or as the Arabs say from «صرصر» , «صر الباب» or «صر صر الباب» , when a sound comes from the door upon closing, like «كبكبته» is derived from «كب» . In Surah Al-A'raf, the word «فمرت به‏» means "she kept moving about," "completed the period of pregnancy." (In Surah Al-A'raf) the word «أن لا تسجد‏» means «أن تسجد‏.‏» , that is, "What prevented you from prostrating to him?" The word «لا» here is extra.