مدة العقد وبند العقد مهمان.

It is a nominal sentence in Arabic, meaning a sentence built without an explicit present-tense verb.

• مدة العقد وبند العقد = the subject part
• مهمان = the predicate, meaning important

So the structure is basically:

• [subject] + [predicate]
• مدة العقد وبند العقد + مهمان

In natural English, we add are, but Arabic does not use a present-tense to be here.

In Modern Standard Arabic, the verb to be is usually not expressed in the present tense.

So:

• مدة العقد وبند العقد مهمان
  literally looks like: The contract duration and the contract clause important
• but it means: The contract duration and the contract clause are important

If you wanted the past, Arabic would use a verb, for example:

• كانا مهمين = they were important

Because مدة العقد is an iḍāfa construction, often called a genitive/possessive construction.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun gives the whole phrase its definiteness

So:

• مدة العقد = the duration of the contract
• not المدة العقد

The first word مدة is definite here because the whole phrase is made definite by العقد.

Both happen because مدة is the first term of an iḍāfa.

1. No tanwīn
   In iḍāfa, the first noun does not take tanwīn.

   So you get:

• مدةُ العقدِ
• not مدةٌ العقدِ

2. The tāʾ marbūṭa is pronounced as t
   When a word ending in ة is followed directly in connection, especially in iḍāfa, that ending is pronounced t.

So مدة العقد is pronounced approximately:

• muddat al-ʿaqd

not just mudda.

Because it is the second noun in an iḍāfa construction.

In مدة العقد:

• مدة = first term of iḍāfa
• العقد = second term of iḍāfa, so it is genitive

The same applies in بند العقد.

If full case endings were written, you would have:

• مدةُ العقدِ
• بندُ العقدِ

So the ـِ ending on العقدِ is there because of the iḍāfa relationship.

Yes, Arabic can avoid repeating it in some contexts, but repeating it is very clear and natural.

This sentence says:

• مدة العقد وبند العقد

That explicitly means:

• the duration of the contract and the clause/provision of the contract

Other possible phrasings include:

• مدة العقد وبنده = the duration of the contract and its clause
• مدة العقد والبند = possibly understood as the duration of the contract and the clause, depending on context

Repeating العقد makes the relationship completely explicit and avoids ambiguity.

Because the sentence is talking about two things:

1. مدة العقد
2. بند العقد

When two nouns are joined by و and treated as a pair, Arabic can use a dual predicate.

So:

• مهمان = important for two
• singular would be مهم
• plural would be مهمون / مهمين depending on case

Here, the meaning is:

• Both the contract duration and the contract clause are important

Because the two nouns have mixed grammatical gender:

• مدة is feminine
• بند is masculine

When Arabic refers to a mixed pair, the default agreement is usually masculine.

So the adjective becomes:

• مهمان = masculine dual

If both nouns were feminine, then مهمتان would be expected.

Because مهمان is in the nominative dual.

In Arabic, the dual has different endings depending on case:

• ـان in the nominative
• ـين in the accusative and genitive

Here, مهمان is the predicate of a nominal sentence, so it is nominative.

Compare:

• هما مهمان = they are important
• رأيتُهما مهمين = I saw them important / I saw that they were important

So in this sentence, ـان is correct.

Because مهمان is not acting like an adjective directly attached to one noun. It is the predicate of the whole sentence.

English often says:

• The contract duration and clause are important

Arabic does the same idea with a nominal sentence:

• مدة العقد وبند العقد مهمان

If you wanted a directly attached adjective phrase, the structure would be different.

So here مهمان describes the whole pair together, not just one noun right next to it.

In this context, بند usually means:

• clause
• provision
• sometimes item

So بند العقد is best understood as:

• a clause of the contract
• a provision of the contract

In legal or formal language, clause or provision is often the best translation.

With full case endings, it would be:

• مُدَّةُ العَقْدِ وَبَنْدُ العَقْدِ مُهِمَّانِ

Breakdown:

• مدةُ = nominative, first noun of the first iḍāfa
• العقدِ = genitive, second noun of the first iḍāfa
• بندُ = nominative, first noun of the second iḍāfa
• العقدِ = genitive, second noun of the second iḍāfa
• مهمانِ = nominative dual predicate

In normal Arabic writing, these short vowels are often omitted, so you usually see:

• مدة العقد وبند العقد مهمان