Why was the word "سوط" (sawṭ) written with a "س" (sīn) in the noble verse, "So your Lord poured upon them a scourge of torment" [Qur'an 89:13], and not written as "صوت" (ṣawt)?

The phrase "whip of torment" (سَوْط عذاب) is mentioned in Surat Al-Fajr (verse 13) in the context of discussing tyrannical nations like 'Ad, Thamud, and Pharaoh, whom Allah punished due to their transgression and corruption. The word "whip" here refers to the well-known instrument used for striking. Commentators have interpreted it as a severe and intense torment that afflicts and crushes them. The choice of this word is due to the fact that lashing with whips was a painful and known form of punishment among the Arabs addressed by the Qur'an. Thus, it came to be used to denote the severity and pervasiveness of torment, regardless of its actual type. As for writing "sawt" (سَوْط) with a "seen" (س) and not "sawṭ" (صَوْت) with a "sad" (ص), it is because the word means the aforementioned instrument, not an audible sound.