Learn Hardcore Farsi: اگر وقت نداری، امشب دیر بیا. - If you don’t have time, come late tonight.

اگر introduces a conditional clause: اگر + (statement) = if ….
In everyday speech it can be omitted if the if-meaning is obvious from context, but in writing and careful speech it’s usually kept:

اگر وقت نداری، … = If you don’t have time, …
(colloquial) وقت نداری؟ امشب دیر بیا. can still imply the condition, but it’s less explicitly if.

Why is it وقت نداری and not something like “you are not having time”?

Persian commonly expresses to have with داشتن (to have) and a direct object:

وقت داری = you have time
وقت نداری = you don’t have time

So it’s literally If you don’t have time…, not “you aren’t having time.”

How is نداری formed? What are its parts?

نداری = نه/نـ (negative prefix na-/ne-) + داری (you have)

داری is the present tense of داشتن for you (singular).
So نداری = you don’t have.

Is نداری informal? What would be the more formal/polite version?

Yes. نداری / بیا are addressed to you (singular, informal).
Formal/polite equivalents:

اگر وقت ندارید، امشب دیر بیایید. (to one person politely, or to multiple people)

What exactly is بیا grammatically?

بیا is the imperative (command/request) form of آمدن (to come) for you (singular informal).
So دیر بیا = come late / come later (depending on context).

Why is it دیر بیا and not دیرتر بیا?

They’re different:

دیر بیا = come late (i.e., at a late time)
دیرتر بیا = come later (i.e., later than some reference time, usually “later than planned/than now”)

In many real contexts English come later might map more naturally to دیرتر بیا, but دیر بیا is still common and can imply “don’t come early; come at a late hour.”

Does دیر mean “late” or “slow”? How do I know?

دیر most often means late (time-related):

دیر آمد = he came late
It can also be part of expressions like دیر فهمیدن (to realize late).
“Slow” is usually آهسته or کند. Here, with بیا (come), دیر is clearly late.

What’s the role of امشب in the sentence, and where can it go?

امشب means tonight and sets the time frame for the main clause. It’s flexible in position:

اگر وقت نداری، امشب دیر بیا. (common)
امشب اگر وقت نداری، دیر بیا. (also possible, slightly different emphasis)

Why is there a comma, and is it required?

The comma separates the conditional clause from the main clause, like in English:

If you don’t have time, come late tonight.

In Persian writing, it’s common (and helpful) but not absolutely required in informal contexts. It improves readability.

Is this sentence a command, a suggestion, or permission?

Grammatically it’s an imperative, so it’s a command/request. Pragmatically, it often functions as a suggestion or permission, depending on tone:

Said gently: “No worries—come later tonight.”
Said firmly: “Don’t come early; come late.”

How do I pronounce this sentence (roughly), and where is the stress?

One common colloquial reading:

agar vaght nadâri, emšab dir biyâ.

Stress is generally on the last syllable of many words/phrases in natural speech, but Persian stress is not as rigid as English. Key points:

vaght has a final consonant cluster; the gh is a voiced uvular sound (often approximated by learners as a strong g/k in the throat).
biyâ ends with â (long a as in “father”).

Could the meaning change if I replace وقت with something else?

Yes—وقت is specifically time (availability). Alternatives change nuance:

اگر فرصت نداری، … (فرصت = opportunity/free time; slightly more formal)
اگر حوصله نداری، … (حوصله = patience/energy/mood; meaning shifts to “If you’re not up for it…”)

In your sentence, وقت keeps it about scheduling/time availability.