وَلَا يَجُوزُ اسْتِعْمَالُ الْمُنْفَصِلِ إِلَّا عِنْدَ تَعَذُّرِ الْمُتَّصِلِ، كَـ «إِيَّاكَ نَعْبُدُ»، وَ«مَا ضَرَبَكَ إِلَّا أَنَا».
Translation: The detached pronoun is used when attachment is not possible, as in “You alone we worship” and “It was only I who struck you.”
The source rule prefers an attached pronoun when attachment is grammatically available; detachment is used where attachment cannot serve the construction.
إِيَّاكَ نَعْبُدُ places the object first for emphasis and restriction. «نَعْبُدُكَ» does not express that word-order emphasis in the same way.