Wonder is expressed by two fixed patterns: mā afʿalahu, as in mā ajmala l-samāʾa, and afʿil bihi, as in ajmil bil-samāʾi. In the first, mā is an indefinite subject, the verb is frozen with an obligatorily concealed doer, and the noun after it is the object; in the second the bāʾ is redundant.
Arabic expresses wonder through two frozen patterns whose analysis never changes, which makes this one of the few chapters you can finish and be finished with. The difficulty is elsewhere: both patterns look like something they are not. In mā ajmala l-samāʾa the middle word looks like an adjective and is a verb, and in ajmil bi-l-samāʾi the last word looks genitive and is a doer.
mā afʿalahu, where mā is a subject, afʿala is a past-tense verb, and the noun after it is its object.
By the end of this lesson
مَا أَجْمَلَ السَّمَاءَ
mā ajmala l-samāʾa
How beautiful the sky is.
ما نكرة تامة بمعنى شيء مبنية على السكون في محل رفع مبتدأ، أجملَ فعل ماضٍ مبني على الفتح والفاعل ضمير مستتر وجوبًا تقديره هو يعود على ما، السماءَ مفعول به منصوب وعلامة نصبه الفتحة الظاهرة، وجملة أجمل السماءَ في محل رفع خبر.
Read the vowels rather than the shape. ajmala with a fatḥa is a verb; ajmalu with a ḍamma would be the elative. Everything downstream follows from that one distinction, including why al-samāʾa is accusative.
afʿil bihi, an imperative in form with a past meaning, where the bāʾ is redundant and what follows is the doer.
أَجْمِلْ بِالسَّمَاءِ
ajmil bi-l-samāʾi
How beautiful the sky is.
أجملْ فعل ماضٍ جاء على صورة الأمر مبني على السكون، الباء حرف جر زائد، السماءِ فاعل مرفوع محلًّا مجرور لفظًا وعلامة جره الكسرة الظاهرة.
A redundant preposition adds emphasis without changing the role, so the word carries a genitive ending while functioning as the doer. Grammarians write this as marfūʿ maḥallan majrūr lafẓan, nominative in position and genitive in form.
فَمَا أَصْبَرَهُمْ عَلَى النَّارِ
fa-mā aṣbarahum ʿalā l-nār
How bold they are in facing the Fire.
الفاء استئنافية، ما نكرة تامة للتعجب في محل رفع مبتدأ، أصبرَ فعل ماضٍ مبني على الفتح والفاعل ضمير مستتر تقديره هو، والهاء ضمير متصل في محل نصب مفعول به، على النارِ جار ومجرور متعلقان بأصبر، وجملة أصبرهم في محل رفع خبر.
Here the object is a pronoun rather than an explicit noun, which changes nothing in the analysis: the pronoun is built in the position of accusative. Notice also that a prepositional phrase attaches to the verb without breaking the pattern, one of the few separations the grammarians permit.
Check yourself
Is akrama here a verb or an elative, and what follows from your answer?
مَا أَكْرَمَ خَالِدًا
A past-tense verb, so khālidan is its object in the accusative.
The fatḥa on akrama settles it. Were it an elative, the following noun could not be accusative. Every part of the analysis, including the hidden doer referring to mā, depends on reading that one vowel correctly.
A verb must satisfy six conditions. When it fails, wonder is expressed through a helper verb and the original becomes a verbal noun.
مَا أَشَدَّ حُمْرَةَ الْوَرْدِ
mā ashadda ḥumrata l-wardi
How intensely red the rose is.
ما نكرة تامة في محل رفع مبتدأ، أشدَّ فعل ماضٍ مبني على الفتح والفاعل ضمير مستتر تقديره هو، حمرةَ مفعول به منصوب وهو مضاف، الوردِ مضاف إليه مجرور.
The verb iḥmarra is a colour on the pattern afʿal, so wonder cannot be built from it directly. The helper ashadda carries the pattern and the original meaning moves into the verbal noun ḥumra, which becomes the object.
Three errors, and the first is by far the most frequent.
The two patterns and the six conditions are given in these texts.
A rule is clearest in a text you already know by heart. Each ayah below contains the very construction this lesson teaches, and every one has a full word-by-word i'rab on this site. Read the ayah first and try to find the construction yourself, then open its i'rab to check.
Common questions
mā afʿalahu, as in mā ajmala l-samāʾa, and afʿil bihi, as in ajmil bi-l-samāʾi. Both express the same wonder and both are analysed in fixed ways that never vary, which is what makes the chapter learnable in a single sitting.
An indefinite noun conveying wonder, built in the position of nominative as the subject. The majority describe it as mā al-taʿajjubiyya, meaning something like "what a thing". Parsing it as an interrogative or a negative here is an error.
Because ajmala is a past-tense verb here, not an elative adjective, and al-samāʾa is its object. The doer is a hidden pronoun referring back to mā. This is the single most useful fact in the chapter, since the form looks like the comparative ajmal.
ajmil is formally an imperative but carries a past-tense meaning. The bāʾ is a redundant preposition, and what follows is nominative in position as the doer, though genitive in form. So in ajmil bi-l-samāʾi, al-samāʾi is the doer in position.
Six, as the grammarians count them: three-lettered, fully inflecting, affirmable, complete rather than defective, not colour or defect on the pattern afʿal, and not passive. A verb failing any of them is expressed through a helper, as in mā ashadda ḥumrata l-wardi.
Very little. The two patterns are treated almost as fixed formulas, and grammarians permit separation only in narrow cases such as an adverbial or a prepositional phrase attached to the verb. Otherwise the pattern must stay intact.