In short

English builds a passive with two words - “was written”. Arabic rebuilds the one word from the inside: كَتَبَ becomes كُتِبَ، يَكْتُبُ becomes يُكْتَبُ. Nothing is added and nothing is removed; only the vowels change. And the doer does not get demoted to a “by” phrase - it disappears completely. That is what the Arabic name says: المَبْنِيُّ لِلْمَجْهولِ, “built for the unknown”, against المَبْنِيُّ لِلْمَعْلومِ, “built for the known”. What used to be the object then steps into the empty subject slot, takes the nominative, and is called نائِبُ الفاعِلِ - the deputy agent.

This is a reading skill before it is a writing skill. News reports, official prose, science and law run on the passive, and two of the commonest verbs in everyday MSA are passives you have already been using as phrases: وُلِدَ “he was born” (lesson 27) and لا يوجَدُ “there is no” (lesson 17). The mechanics are small - one vowel recipe and two riders - and once you have them, every verb in the language, weak roots included, is covered.

The rule

1. The recipe, both tenses. Learn it as two syllables and you have the whole system.

• الماضي: a ḍamma on the first letter, a kasra on the letter before the last. كَتَبَ → كُتِبَ، فَتَحَ → فُتِحَ، عَلَّمَ → عُلِّمَ، أَرْسَلَ → أُرْسِلَ.
• المُضارِع: a ḍamma on the prefix letter, a fatḥa on the letter before the last. يَكْتُبُ → يُكْتَبُ، يُعَلِّمُ → يُعَلَّمُ، يُشاهِدُ → يُشاهَدُ، يُرْسِلُ → يُرْسَلُ.

“The letter before the last” means the last letter of the word itself, not the case ending - in كُتِبَ the final فَتْحة is the past-tense ending, and the kasra sits on the ت before it. Say كُتِبَ - يُكْتَبُ out loud a few times: u-i in the past, u-a in the present. Every other statement in this lesson is a footnote to those two syllables.

2. Rider one: a word starting with هَمْزَةُ الوَصْلِ takes a second ḍamma, on the third letter. Forms VII, VIII, IX and X begin their past tense with the propping alif of lesson 48, which has no vowel of its own to change. So Arabic gives the alif the ḍamma and gives one to the third letter as well: اِنْتَخَبَ → اُنْتُخِبَ، اِسْتَخْدَمَ → اُسْتُخْدِمَ، اِعْتَقَلَ → اُعْتُقِلَ. Note the spelling: the alif stays bare (وَصْل), it simply carries a ḍamma instead of its usual kasra. The imperfect has no such alif and needs no rider: يُنْتَخَبُ، يُسْتَخْدَمُ.

3. Rider two: a past tense starting with an added تَ takes the second ḍamma on the letter right after that تَ. The تَ is the first letter, so it takes the ordinary ḍamma of rule 1, and the first radical takes the extra one. This covers Forms V and VI: تَعَلَّمَ → تُعُلِّمَ، تَبادَلَ → تُبودِلَ. These passives are rare, but one of them is everyday newspaper Arabic: تُوُفِّيَ “he passed away”, the passive of تَوَفّى.

4. Long vowels bend to fit the recipe. Where the pattern has a long ا that must now carry a ḍamma, it surfaces as و: Form III شاهَدَ → شوهِدَ، ساعَدَ → سوعِدَ; Form VI تَبادَلَ → تُبودِلَ. In the imperfect the ا is unaffected, because a fatḥa is exactly what it already holds: يُشاهَدُ، يُتَبادَلُ. Nothing here is an exception - the vowel recipe simply wins.

5. Forms VII and IX have no passive in ordinary use. اِنْكَسَرَ already means “it broke, with no doer named”, and اِحْمَرَّ “it turned red” has no object to promote. Both are intransitive and already agentless, so a dictionary or a conjugator simply prints no مَجْهول column for them. If a text needs “the door was opened by someone unnamed”, the choice is فُتِحَ البابُ (true passive of Form I) or اِنْفَتَحَ البابُ (Form VII, “the door opened”). The shape اُنْفُتِحَ is not something you will meet.

6. A ḍamma prefix does not by itself mean passive. Lesson 46 warned about this and here is where it bites. Forms II, III and IV and the quadriliteral take a ḍamma prefix in the active too. What tells them apart is the vowel before the last letter - kasra for those actives, fatḥa for any passive:

يُعَلِّمُ “teaches” against يُعَلَّمُ “is taught”; يُشاهِدُ “watches” against يُشاهَدُ “is watched”; يُرْسِلُ “sends” against يُرْسَلُ “is sent”; يُتَرْجِمُ “translates” against يُتَرْجَمُ “is translated”. One mark, two opposite meanings - which is the best argument this path can make for printing the تَشْكيل.

7. نائِبُ الفاعِلِ is مَرْفوع, and the verb agrees with it. Take كَتَبَ الطّالِبُ الرِّسالَةَ. Delete the agent, and الرِّسالَةَ - accusative because it was the object - moves into the vacated slot and becomes مَرْفوع: كُتِبَتِ الرِّسالَةُ. Two things changed together, and learners usually do only one of them: the case and the agreement. The verb now agrees in gender with its deputy, so كُتِبَتْ with a تاء, not كُتِبَ.

Agreement follows the ordinary rules you already have. Verb before its deputy stays singular: اُعْتُقِلَ المُتَّهَمونَ. Non-human plurals take feminine singular agreement (lesson 11): تُباعُ الكُتُبُ، أُرْسِلَتِ الرَّسائِلُ، تُرْجِمَتْ رِواياتُهُ. A deputy agent behaves in every respect like any other subject of a verbal sentence (lesson 19) - it is only the verb’s shape that is unusual.

8. When the verb reaches its object through a preposition, the جارّ والمَجْرور takes over. Verbs like عَثَرَ عَلى “find”, أَشارَ إِلى “point out”, أَعْلَنَ عَنْ “announce” have no accusative object to promote (lesson 30), so the prepositional phrase stands in as the deputy - and because a شِبْه جُمْلَة has no gender or number of its own, the verb freezes in the masculine singular: عُثِرَ عَلَى الحَقيبَةِ، أُشيرَ إِلى أَنَّ…، أُعْلِنَ عَنْ نَتائِجِ الاِنْتِخاباتِ. Writing عُثِرَتِ الحَقيبَةُ is the standard error here: الحَقيبَة never was an object and cannot become a deputy.

9. Two objects, one deputy. Verbs that take two accusatives - أَعْطى، مَنَحَ، عَلَّمَ - promote the first and leave the second where it was: أَعْطى المُديرُ الطّالِبَ جائِزَةً → أُعْطِيَ الطّالِبُ جائِزَةً. The second accusative is not a leftover mistake; it simply has no slot to move into. (The ظَنَّ family, whose two accusatives behave differently, is lesson 59.)

10. The passive normally names no agent. This is the point where English habits do the most damage. The passive exists precisely because the doer is unknown, irrelevant or deliberately unsaid, so classical usage attaches no “by” phrase at all - if you want to name the doer, use the active. Two modern workarounds exist and both need care:

• بِواسِطَةِ means “by means of, via” and belongs with instruments and channels: أُرْسِلَتِ الوَثائِقُ بِواسِطَةِ البَريدِ الإِلِكْتْرونِيِّ. Using it for a person - قُتِلَ بِواسِطَةِ الجُنودِ - is a translation reflex, and it reads badly.
• مِنْ قِبَلِ + genitive (اُعْتُقِلَ الرَّجُلُ مِنْ قِبَلِ الشُّرْطَةِ) is what the press actually writes. Recognise it; it is press register and belongs to lesson 69, not to your own neutral prose.

11. Moods and قَدْ change nothing internal. The passive takes the same endings as the active, because the endings never were the passive’s business: لَنْ يُباعَ البَيْتُ (subjunctive, lesson 33), لَمْ يُنْشَرِ الخَبَرُ (jussive, lesson 35), قَدْ كُتِبَتِ الرِّسالَةُ (lesson 45), كانَ البابُ قَدْ فُتِحَ. There is no passive imperative - you cannot order someone to undergo something.

12. Unvocalized, the two voices are the same letters. كتب الدرس is either كَتَبَ الدَّرْسَ “he wrote the lesson” or كُتِبَ الدَّرْسُ “the lesson was written”, and only the context decides. This is the single most useful case of the unvocalized-reading skill: look for a named agent (if one is present, the verb is active), and read on - a following مِنْ قِبَلِ، أَمْسِ في الجَريدَةِ or a lone noun after the verb with nothing else to be the doer all point to a passive. لا يوجَدُ leaves nothing to resolve at all - its active يَجِدُ is written without the و - and ولد followed by a date or a place is read وُلِدَ as a matter of course.

13. Left to other lessons. The passive participle مَفْعولٌ - مَكْتوبٌ، مُسْتَخْدَمٌ - covers a lot of the same ground with a noun instead of a verb, and it is lesson 53. Passives of the ظَنَّ family are lesson 59.

Forms & patterns

The recipe in one table. Everything else follows from these four cells.

The forms, active against passive. Form I here is كَتَبَ, then عَلَّمَ (II), شاهَدَ (III), أَرْسَلَ (IV), تَعَلَّمَ (V), تَبادَلَ (VI), اِنْكَسَرَ (VII), اِنْتَخَبَ (VIII), اِسْتَخْدَمَ (X) and the quadriliteral تَرْجَمَ. Form IX is left out for the same reason as VII.

A full person paradigm - سُئِلَ / يُسْأَلُ, “to be asked”. The endings are the ones you learned in lessons 14 and 18, unchanged. Only the inside of the stem is new. The dual and the second-person feminine plural are omitted; they take the endings you already know.

Weak and awkward roots. This is where the passive is easier than the active: whatever the active class did, the passive collapses it into one shape. Every أَجْوَف verb that shortens in the active - Form I and measures IV, VIII and X (lesson 50) - is قيلَ / يُقالُ shaped: ي in the past, ا in the present. Every ناقِص verb ends in ـِيَ in the past and in ـى in the present, whichever letter its active used.

The hamzated verbs change seat, not sound: a hamza with a kasra on it or before it sits on a ي (سُئِلَ، قُرِئَ), and a hamza with a sukūn after a ḍamma sits on a و (يُؤْخَذُ, from أَخَذَ).

Examples

Common mistakes

• كُتِبَ الرِّسالَةَ -> كُتِبَتِ الرِّسالَةُ - the old object is now نائِبُ الفاعِلِ. Two things must change at once: the case becomes مَرْفوع, and the verb agrees with it in gender.
• يُكْتِبُ الدَّرْسُ -> يُكْتَبُ الدَّرْسُ - the imperfect passive has a fatḥa before the last letter. A kasra there gives an active verb of a different form, not a passive.
• إِنْتُخِبَ الرَّئيسُ -> اُنْتُخِبَ الرَّئيسُ - that alif is هَمْزَةُ وَصْلٍ (lesson 48) and is written bare in the passive exactly as in the active; only its vowel changes, kasra to ḍamma.
• اِنْتُخِبَ الرَّئيسُ -> اُنْتُخِبَ الرَّئيسُ - and the ḍamma goes on the alif as well as on the third letter. Same for Form X: اُسْتُخْدِمَ، not اِسْتُخْدِمَ.
• قُوِلَ لَنا إِنَّهُ مُسافِرٌ -> قيلَ لَنا إِنَّهُ مُسافِرٌ - a hollow root cannot keep its middle و here; the past passive of a Form I أَجْوَف verb is the قيلَ shape.
• يُقولُ إِنَّ الاِجْتِماعَ غَدًا -> يُقالُ إِنَّ الاِجْتِماعَ غَدًا - and the imperfect passive of a hollow verb is the يُقالُ shape, with ا. يَقولُ with a fatḥa prefix is the active.
• كَيْفَ يُدْعي هٰذَا الطَّبَقُ؟ -> كَيْفَ يُدْعى هٰذَا الطَّبَقُ؟ - the imperfect passive of a ناقِص verb always ends in أَلِف مَقْصورة, never in ي, whatever the active ending was.
• يُباعُ الكُتُبُ هُنا -> تُباعُ الكُتُبُ هُنا - a non-human plural deputy agent takes feminine singular agreement, just like any other subject (lesson 11).
• قُتِلَ الرَّجُلُ بِواسِطَةِ الجُنودِ -> قَتَلَ الجُنودُ الرَّجُلَ - the Arabic passive names no agent, and بِواسِطة is “by means of”, for instruments and channels. Name the doer and you want the active.
• اُنْفُتِحَ البابُ -> فُتِحَ البابُ - Form VII is intransitive and already agentless, so it has no passive to build. Use the Form I passive, or اِنْفَتَحَ البابُ.

Tips

• Drill the recipe as sound, not as a list: u-i for the past, u-a for the present. كُتِبَ / يُكْتَبُ is the tuning fork - hum it and any verb you meet falls into place.
• Conjugate the active you already know, then repaint the vowels. The endings, the personal prefixes and the moods are untouched, so there is no second paradigm to memorise.
• A ḍamma on the prefix is not a passive on its own - يُعَلِّمُ، يُشاهِدُ، يُرْسِلُ، يُتَرْجِمُ are all active. Your eye should go to the vowel before the last letter every time.
• Weak roots are a relief here. Every hollow verb that shortens in the active is قيلَ - يُقالُ, every defective verb is رُمِيَ - يُرْمى, and the active’s و/ي split stops mattering.
• Read a news page and collect the frozen press formulas whole: يُذْكَرُ أَنَّ، أُشيرَ إِلى أَنَّ، أُعْلِنَ عَنْ، عُثِرَ عَلى. They are passives with a prepositional deputy and they never change shape.
• If you are unsure of a vowelled passive, look the verb up rather than guess - a conjugator such as qutrub.arabeyes.org prints the المَجْهول column beside the المَعْلوم one.
• A labelled contrast, not something to imitate: the internal passive has largely disappeared from the spoken dialects, which use an اِنْفَعَل / اِتْفَعَل type verb instead. In writing, MSA expects the vowel-change passive.
• Ignore for now the passive participle مَكْتوبٌ (lesson 53) and any deputy agent that is not a promoted object. Object-to-subject is the case that covers almost everything you will read.