In فِي عَمَدٍ مُمَدَّدَةٍ, tanwīn before mīm triggers idghām with ghunnah, just as tanwīn before wāw belongs to the same nasalized group.
The doubled dāl in مُمَدَّدَةٍ does not itself carry the special nasalization of doubled nūn or mīm. Apply each rule only at its actual trigger.
At a pause on the final word, tāʾ marbūṭah is read as a sākin hāʾ; the final kasrah-tanwīn is not retained.
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ʿAmadin mumaddadah: tanwīn before mīm
Al-Māʿūn and Al-Humazah: Applied Assimilation, Concealment, Madd and Hāʾ Rules
In فِي عَمَدٍ مُمَدَّدَةٍ, tanwīn before mīm triggers idghām with ghunnah, just as tanwīn before wāw belongs to the same nasalized group.
The doubled dāl in مُمَدَّدَةٍ does not itself carry the special nasalization of doubled nūn or mīm. Apply each rule only at its actual trigger.
At a pause on the final word, tāʾ marbūṭah is read as a sākin hāʾ; the final kasrah-tanwīn is not retained.