The pronoun hāʾ
ۥۦهاء الكناية
hāʾ al-kināyah
This is the whole chapter that the two ṣilah rules belong to. The default is that the hāʾ takes a glide when it sits between two vowelled letters and does not when it sits next to a vowelless one — but individual readers extend or withhold the glide in specific words, and those exceptions are named one by one.
Example
فِيهِۦ
al-Baqarah 2:2
Ibn Kathīr gives the glide here where Ḥafṣ does not — one of the first divergences in the muṣḥaf.