من امشب دیر میرسم، پس لطفا در را قفل نکن تا خودم بیایم.

In Persian, the present tense is very often used for a planned or expected future event, especially when there is already a time word like امشب (tonight).

So:

من امشب دیر می‌رسم
literally: I arrive late tonight
natural English: I’ll arrive late tonight

A more explicit future form is possible, such as خواهم رسید, but that sounds more formal or bookish here.

You can leave it out.

می‌رسم already shows I arrive / I will arrive, so the subject is built into the verb ending. Persian often drops subject pronouns when they are clear from the verb.

So both are possible:

من امشب دیر می‌رسم
امشب دیر می‌رسم

Using من adds a little emphasis or clarity.

امشب means tonight.

It is made from ام + شب, and it refers to the evening/night of the current day.

So:

امشب = tonight
امروز = today
امسال = this year

In this sentence, امشب sets the time and helps show that می‌رسم is talking about the future.

دیر means late.

In Persian, adverbs often come before the verb, so:

دیر می‌رسم = I arrive late / I’ll be late arriving

That word order is very normal in Persian.

Compare:

زود می‌آیم = I come early / I’ll come early
دیر می‌رسم = I arrive late

را marks a specific direct object.

Here:

در = door
در را = the door

So را shows that door is the thing affected by the action lock.

This does not mean to the door. It is an object marker, not a preposition.

A very literal breakdown is:

در را قفل نکن
door + object marker + lock + don’t
= Don’t lock the door

In speech, را often sounds like رو, so you may hear:

در رو قفل نکن

قفل کردن means to lock.

This is a compound verb:

• قفل = lock
• کردن = to do

The imperative is made with کن from کردن:

قفل کن = lock!
قفل نکن = don’t lock!

So نکن is the negative imperative form: don’t do.

In this sentence:

در را قفل نکن = Don’t lock the door

Because لطفا only means please. It does not make the verb formal by itself.

So:

قفل نکن = informal singular: don’t lock
قفل نکنید = formal or plural: don’t lock

That means:

لطفا در را قفل نکن = Please don’t lock the door
but still addressed informally to one person.

If you wanted a more polite/formal version, you would say:

لطفاً در را قفل نکنید

پس means so, therefore, or then.

It connects the first clause to the result or request:

من امشب دیر می‌رسم، پس...
= I’ll arrive late tonight, so...

It is a very common connector in Persian.

After تا, Persian often uses the subjunctive when talking about something not yet completed, expected, intended, or dependent on another action.

So:

بیایم is the subjunctive form of آمدن for I.

That is why:

تا خودم بیایم
is natural here, not تا خودم می‌آیم.

A learner-friendly way to think about it is:

• می‌آیم = I come / I am coming / I will come
• بیایم = that I come / until I come / so that I may come

The exact English translation depends on context, but the subjunctive after تا is very common.

It can feel like either one, depending on how you translate it.

In this sentence, the most natural English meaning is:

Please don’t lock the door until I come / until I get there myself.

But there is also a slight purpose flavor:

Please don’t lock the door so that I can come in myself.

So تا here links the request to a later event. In many real sentences, the line between until and so that is not completely sharp.

خودم means myself.

It adds emphasis:

تا خودم بیایم = until I myself come / until I get there myself

Without خودم, the sentence still works:

تا بیایم

But خودم suggests something like:

• I personally will come
• not someone else
• wait for me specifically

So it adds emphasis, not a completely new meaning.

Persian is generally subject–object–verb, and important time words often come early.

A rough breakdown is:

من = I
امشب = tonight
دیر = late
می‌رسم = arrive / will arrive
پس = so
لطفا = please
در را = the door
قفل نکن = don’t lock
تا = until / so that
خودم = myself
بیایم = I come

So the literal order feels like:

I tonight late arrive, so please the door don’t lock until I myself come.

That word order is normal in Persian, even though English arranges it differently.

In standard Persian spelling, می‌رسم with a half-space is preferred.

So the standard written form is:

می‌رسم

But in casual typing, many people write:

میرسم

Both are understood.

The same kind of thing happens with other words in the sentence:

• لطفاً is the more formal spelling, but لطفا is very common
• بیایم is standard written Persian
• in colloquial speech, you may hear بیام

So the sentence is fine, but some forms are more formal/standard than others.