If the first hamzah is waṣl and the second qaṭʿ, the book distinguishes a fresh start from connected recitation. A relevant replacement occurs on starting at that word, but when joined from the previous word the waṣl drops and that initial-form replacement no longer applies in the same way.
The same written word can thus behave differently depending on the reading boundary.
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Waṣl before qaṭʿ
Rules of Hamzah — Taḥqīq, Tashīl, Ibdāl and Hamzat al-Waṣl
If the first hamzah is waṣl and the second qaṭʿ, the book distinguishes a fresh start from connected recitation. A relevant replacement occurs on starting at that word, but when joined from the previous word the waṣl drops and that initial-form replacement no longer applies in the same way.
The same written word can thus behave differently depending on the reading boundary.