He asks: what is the ruling on someone who describes people as "original" or "of low lineage"?

Whether in dealings or in marriage.

The Prophet ﷺ said: There are two things in my umma that are acts of disbelief: attacking people's lineage and wailing over the dead.

It is never allowed to attack people's lineage, especially since a person's origin, background, and lineage are things he has no merit in.

There is no merit in it for a person to boast about.

The point is that it is not allowed for a person to attack people's lineage.

Criticizing people's lineage has two situations. The first is to cast doubt on their lineage.

Without any reason. The second is to insult them or criticize their lineage in a way that shows contempt for them.

Among them is the saying of the Prophet ﷺ: Arrogance is rejecting the truth and belittling.

People, meaning despising people. So it is not allowed for a person to despise others, and we seek refuge with Allah.

And he says to Yahya ibn Ma'in.

I sat with Ahmad.

For twenty years, not once did he boast to us about his lineage, because Ahmad was Arab, while Yahya ibn Ma'in was not Arab.

Ali ibn al-Madini was not Arab either. He said: Not once did he boast to us, saying: I am Arab and you are not. I never heard it from him, in twenty years.

So we take these as examples, and Allah is the one whose help is sought.