نعرف بعضنا منذ زمن

You use it like an adjective describing your relationship. It usually comes after mentioning who you are talking about. You can say it about a friend, a neighbor, or even a colleague. It is very flexible in its grammar. You don't need complex verbs here. Just the active participle عارفين does all the heavy lifting. It functions as a bridge to explain why you are so relaxed around someone.

Use it when someone asks how you two met. It is perfect for weddings or big family dinners. If you are at a restaurant and the waiter recognizes you, tell your friends this. It adds a layer of "insider" status to your social interactions. It is also great for breaking the ice in new groups. It explains why you might be finishing each other's sentences.

Avoid using this for someone you just met recently. Even if you spent a whole weekend together, زمان is for years. Don't use it in a very stiff legal setting. It is a bit too warm for a courtroom or a formal contract signing. Also, don't use it if you actually don't like the person. It usually implies a positive or at least neutral history. Using it for an enemy would just be confusing.

In many Arab cultures, time is the ultimate test of character. A "new" friend is great, but an "old" friend is gold. The word زمان itself is very nostalgic. It evokes memories of old neighborhoods and simpler times. Having someone you've known من زمان is a point of pride. It shows you are loyal and have deep social roots. It reflects a culture where community and longevity are highly valued.

You might hear نعرف بعض من زمان which is the verb version. In Egypt, people might say إحنا عشرة عمر for something even deeper. If you are talking about just one person, say عارفه من زمان. For a female friend, use عارفها من زمان. The core meaning stays the same across these small tweaks. You can also add قوي at the end to mean "a very long time."