What is the difference between "Indeed, I am only a clear warner" and "This is not but a human being like yourselves," and between "Indeed, this is nothing but clear magic" and "This is not but clear magic," especially knowing that "إنْ" (in) takes the place of "ما" (ma), but must have a specific function or other meaning for their combination in Surat Saba, as well as in His saying: "You only wish to be a tyrant in the land and do not wish to be among the reformers"?

Both words "ma" (ما) and "in" (إنْ) are used to negate the present state. Some grammarians other than Sibawayh have made "in" function like "laysa" (ليس) due to their similarity in meaning, as both negate the present state and are followed by a nominal sentence (jumlat al-ibtida').

Perhaps the shift from repeating "ma" to using "in" in some verses is to avoid repetition and diversify the style. Sheikh Fadhel Al-Samarrai has observed that negation with "in" is more emphatic than with "ma." The evidence for this is its frequent association with "illa" (إلا), as in the Almighty's saying: "You are not but humans like us" (إنْ أنتم إلا بشر مثلنا), and His saying: "And there is nothing except that it glorifies His praise" (وإن من شيء إلا يسبح بحمده).