In «تَرْمِيهِمْ بِحِجَارَةٍ», the first word ends with mīm sākinah and the next starts with bāʾ. This gives ikhfāʾ shafawī with ghunnah.
Contrast «أَلَمْ تَرَ» and «عَلَيْهِمْ طَيْرًا», where a different following letter demands clear mīm. Concealment keeps nasalization without creating a separate vowel or nūn. The alif madd and tanwīn in the next word are independent sites requiring their own decisions.
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Tarmīhim bi-ḥijārah: mīm before bāʾ
Al-Fīl and Quraysh: Applied Iẓhār, Ikhfāʾ, Idghām, Madd and Waqf
In «تَرْمِيهِمْ بِحِجَارَةٍ», the first word ends with mīm sākinah and the next starts with bāʾ. This gives ikhfāʾ shafawī with ghunnah.
Contrast «أَلَمْ تَرَ» and «عَلَيْهِمْ طَيْرًا», where a different following letter demands clear mīm. Concealment keeps nasalization without creating a separate vowel or nūn. The alif madd and tanwīn in the next word are independent sites requiring their own decisions.