Rule 1: 1. The maṣdar of Form I
Every verb has a maṣdar, a noun naming the action itself. For Form I there is no single pattern: كَتَبَ gives كِتَابَةٌ writing, دَخَلَ gives دُخُولٌ entering, عَمِلَ gives عَمَلٌ work, صَنَعَ gives صِنَاعَةٌ manufacture, industry, نَجَحَ gives نَجَاحٌ success. The commonest shapes are فَعْلٌ, فُعُولٌ, فِعَالَةٌ, فَعَلٌ and فَعَالٌ, but the Form I maṣdar must be learnt with each verb, and from this lesson the vocabulary lists give it. It is an ordinary noun: it takes the article, tanwīn and the three cases.
اَلْعَمَلُ فِي الْوَرْشَةِ صَعْبٌ وَلٰكِنَّهُ مُفِيدٌ.
al-ʿamalu fi l-warshati ṣaʿbun wa-lākinnahu mufīdun
Work in the workshop is hard, but it is useful.
The maṣdar عَمَلٌ as subject of a nominal sentence.
اَلتِّجَارَةُ مِهْنَةُ أَبِي وَالزِّرَاعَةُ مِهْنَةُ جَدِّي.
at-tijāratu mihnatu abī wa-z-zirāʿatu mihnatu jaddī
Trade is my father's occupation and farming is my grandfather's.
Pattern فِعَالَةٌ, common for crafts and occupations.
نَجَاحُ الصَّانِعِ فِي عَمَلِهِ وَلَيْسَ فِي كَلَامِهِ.
najāḥu ṣ-ṣāniʿi fī ʿamalihi wa-laysa fī kalāmihi
A craftsman's success lies in his work, not in his talk.
كِتَابَةُ الْحُرُوفِ بِالْمِطْرَقَةِ عَلَى الْحَدِيدِ صِنَاعَةٌ قَدِيمَةٌ.
kitābatu l-ḥurūfi bi-l-miṭraqati ʿala l-ḥadīdi ṣināʿatun qadīmatun
Writing letters on iron with a hammer is an ancient craft.
A maṣdar as the first term of an iḍāfa whose second term is its object.
سَمِعْنَا صَوْتَ دُخُولِ الْعُمَّالِ إِلَى الْمَصْنَعِ.
samiʿnā ṣawta dukhūli l-ʿummāli ila l-maṣnaʿi
We heard the sound of the workers entering the factory.
Here the second term of the iḍāfa, الْعُمَّالِ, is the subject of the action.