In عِيشَةٍ رَاضِيَةٍ, tanwīn precedes rāʾ. Rāʾ and lām are the two letters of idghām without ghunnah for nūn sākin/tanwīn.
On joining, the tanwīn nūn assimilates into rāʾ without an independent nasalization. The rāʾ of «رَاضِيَةٍ» has fatḥah, so it is heavy.
Stopping on «عِيشَةٍ» instead changes the final tāʾ marbūṭah to a pronounced hāʾ-sākin; there is then no cross-word idghām.
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Idghām without ghunnah before rāʾ
Al-Qāriʿah and Az-Zalzalah — Comparative Tajwīd Practice
In عِيشَةٍ رَاضِيَةٍ, tanwīn precedes rāʾ. Rāʾ and lām are the two letters of idghām without ghunnah for nūn sākin/tanwīn.
On joining, the tanwīn nūn assimilates into rāʾ without an independent nasalization. The rāʾ of «رَاضِيَةٍ» has fatḥah, so it is heavy.
Stopping on «عِيشَةٍ» instead changes the final tāʾ marbūṭah to a pronounced hāʾ-sākin; there is then no cross-word idghām.