Rule 5: Where a moving wāw or yāʾ is preceded by a quiescent consonant, its vowel is transferred to that preceding consonant in the relevant form. This is naql al-ḥarakah.
يَقْوُلُ → يَقُولُ — he says.
يَبْيِعُ → يَبِيعُ — he sells.
The wāw’s ḍammah passes to qāf in the first example; the yāʾ’s kasrah passes to bāʾ in the second. The weak letter remains as a long vowel, so this is not simple deletion.
Opening interactive controls...
Rule 5: Transfer of the Weak Radical’s Vowel
Hollow Verbs: Seven Iʿlāl Rules and Three Short Paradigms
Rule 5: Where a moving wāw or yāʾ is preceded by a quiescent consonant, its vowel is transferred to that preceding consonant in the relevant form. This is naql al-ḥarakah.
يَقْوُلُ → يَقُولُ — he says.
يَبْيِعُ → يَبِيعُ — he sells.
The wāw’s ḍammah passes to qāf in the first example; the yāʾ’s kasrah passes to bāʾ in the second. The weak letter remains as a long vowel, so this is not simple deletion.