I kinda undrestood this when I noticed this sign:A slave woman giving birth to her mistress .
May Allah protect us
Jibril said this sign to Russul-Allah SAS.
There are more than one interpretation about it.
Those given by Nawawi (r.a.) is that slave-girls will give birth to sons and daughters who will become free and so be the masters of those who bore them.
The word ,,ama,,-slave-girl is also capable of meaning any woman ,servant of Allah SUT i.e. muslima.
And ,,rabba,,-mistress includes the masculine ,,rabb,,-master.
,,When a woman will give birth to her master''
So we can say it will come time when children will have so little respect to their mothers,that they will treat them like servants.
And Allah SUT knows best!