What is the grammatical analysis (اعراب) of the word "عليه" in the tenth verse of Surat Al-Fath, "And whoever fulfills what he has covenanted upon Allah – He will surely give him a great reward," and why is it dammah-ed (مضمومة)?

The prepositional phrase "عليه" (on him/it) is connected to the verb "عاهد" (he covenanted/pledged). Hafs recited "عليهُ" with a dammah (ḍamma) on the hāʾ (ه), maintaining its original vowel. In contrast, the majority of reciters recited "عليهِ" with a kasrah (kasra) on the hāʾ due to its proximity to the yāʾ (ي). It is said that the reason for the dammah is that it is the hāʾ of "هو" (he/it), which inherently has a dammah, while the reason for the kasrah is to accommodate the yāʾ.