Rule 1: 1. Verbal nouns of hollow verbs (middle و or ي)
A Form I verb whose middle radical is و or ي usually has a verbal noun on the pattern فَعْلٌ, in which the weak letter reappears as a consonant: بَاعَ to sell gives بَيْعٌ, سَارَ to go gives سَيْرٌ, قَالَ to say gives قَوْلٌ, صَامَ to fast gives صَوْمٌ, نَامَ to sleep gives نَوْمٌ. A second common pattern is فِعَالَةٌ or فِعَالٌ, in which a و after kasra becomes ي: زَارَ gives زِيَارَةٌ a visit, قَامَ gives قِيَامٌ standing, صَامَ also gives صِيَامٌ. In Forms IV and X the verbal noun ends in ـَةٌ: إِقَامَةٌ residence, establishing, اِسْتِطَاعَةٌ ability, اِسْتِفَادَةٌ benefiting.
كَانَ أَهْلُهَا يَتَوَلَّوْنَ أَمْرَ الْبَيْعِ وَالشِّرَاءِ.
kāna ahluhā yatawallawna amra l-bayʿi wa-sh-shirāʾi
Her family used to take charge of selling and buying.
لَا تَخْرُجُ إِلَّا لِزِيَارَةِ الْأَقَارِبِ.
lā takhruju illā li-ziyārati l-aqāribi
She goes out only to visit relatives.
زِيَارَةٌ from زَارَ: و → ي after kasra.
اَلصَّوْمُ فِي رَمَضَانَ وَالْقِيَامُ فِي لَيَالِيهِ.
aṣ-ṣawmu fī ramaḍāna wa-l-qiyāmu fī layālīhi
Fasting in Ramadan and standing (in prayer) in its nights.
لَيْسَ فِي اسْتِطَاعَةِ نِسَاءِ الْمَدِينَةِ أَنْ يَمْشِينَ فِي الصَّحْرَاءِ.
laysa fī stiṭāʿati nisāʾi l-madīnati an yamshīna fi ṣ-ṣaḥrāʾi
It is not within the ability of the women of the city to walk in the desert.
اِسْتِطَاعَةٌ, Form X verbal noun of اِسْتَطَاعَ.