Из-за спешки я забыл проездной дома.

Из-за means because of and it requires the genitive case.

The noun спешка becomes спешки in the genitive singular:

• спешка = haste, rush
• из-за спешки = because of haste / because I was in a hurry

So this phrase literally works like because of rushing / because of the hurry.

Спешка means haste, rush, or being in a hurry. It is a noun, not a verb.

So из-за спешки does not mean while hurrying word-for-word, but rather because of haste or because I was rushed.

It is a very natural way in Russian to explain that something happened because someone was in a hurry.

Забыл is the perfective past form of забыть, which means to forget in the sense of a completed event.

Here the speaker is talking about one finished action:

• I forgot it

If you used забывал, that would be imperfective and would usually suggest repeated forgetting, process, or background description:

• Я забывал проездной = I used to forget my pass / I was forgetting my pass

So забыл is the correct choice for a single completed mistake.

Here проездной is in the accusative singular, because it is the direct object of забыл:

• забыл что? → проездной

Also, проездной is often short for проездной билет or simply a transport pass/travel pass. In everyday Russian, people very commonly just say проездной.

Because it is an inanimate masculine noun, the accusative form is the same as the nominative:

• nominative: проездной
• accusative: проездной

Historically, it comes from an adjective, but in modern everyday Russian it often functions as a noun by itself.

Originally:

• проездной билет = travel pass / season ticket

In normal speech, билет is often omitted:

• Я забыл проездной = I forgot my travel pass

This kind of shortening is very common in Russian.

This is a very common question.

• дома = at home (location)
• домой = home / to home (direction)

In this sentence, the meaning is that the travel pass was left at home, so Russian uses дома:

• Я забыл проездной дома = I forgot my pass at home

If you said домой, it would suggest motion toward home, which does not fit here.

Here дома means at home. It tells you where the pass was forgotten.

So the structure is:

• я забыл проездной дома
• literally: I forgot the pass at home

It does not mean from home here.

Russian often leaves out possessive words like my, your, his, etc. when the meaning is obvious from context.

So:

• Я забыл проездной naturally means I forgot my pass

You could say мой проездной, but it is often unnecessary unless you want emphasis or contrast:

• Я забыл мой проездной, а не твой = I forgot my pass, not yours

In ordinary speech, leaving out мой is more natural.

The sentence is natural as written, but Russian word order is more flexible than English.

Из-за спешки я забыл проездной дома sounds natural because:

• из-за спешки sets the reason first
• then comes the subject я
• then the action забыл
• then the object проездной
• then the location дома

You could rearrange it, for example:

• Я забыл проездной дома из-за спешки

That is still understandable, but the original order sounds smoother if you want to emphasize the reason first.

No, not in standard Russian.

The normal expression here is из-за спешки = because of haste.

Russian does have expressions with по, but по спешке is not the standard way to say this. A learner should stick with:

• из-за спешки
• в спешке = in a hurry / hurriedly

These are the most useful natural patterns.

Good question. They are close, but not identical.

• забыл проездной дома = I forgot my pass at home
  Focus: the mistake was forgetting it

• оставил проездной дома = I left my pass at home
  Focus: the pass remained at home

In many real situations, both could work. But забыл emphasizes memory/forgetfulness, while оставил emphasizes where the object stayed.

Yes, sometimes.

Russian often drops the subject pronoun when it is clear from the verb form or context:

• Из-за спешки забыл проездной дома

This can sound natural in conversation, especially if it is obvious who is speaking about themselves.

However, keeping я is also completely normal and often clearer for learners:

• Из-за спешки я забыл проездной дома

Very often, yes.

Из-за usually introduces a cause that is problematic, undesirable, or inconvenient:

• из-за дождя = because of the rain
• из-за пробок = because of traffic jams
• из-за спешки = because of haste

So it fits very well here, because forgetting your pass is a negative result.

For neutral or positive causes, Russian often prefers other expressions, such as из-за less often and благодаря for clearly positive causes.

It depends on what is new or important in context, but a natural default pattern would often stress:

• спешки
• проездной
• or дома

For example:

• Из-за спешки я забыл проездной дома.

If the important point is the reason, спешки gets more emphasis. If the important point is what was forgotten, проездной gets more emphasis. If the important point is where it was left, дома gets more emphasis.

Russian stress in a whole sentence is flexible and depends a lot on context.