This excerpt is taken from Sheikh Hafiz Mubashir Hussain Lahori's book Signs of the Day of Judgment in the Light of Authentic Hadith.
Sign of the Day of Judgment: A Slave Girl Will Give Birth to Her Master
وعن أبى هريرة رضى الله عنه قال كان رسول الله صلى الله عليه وسلم يوما بارزا للناس فأتاه رجل فقال : يا رسول الله متى الساعة ؟ قال : ما المسؤول عنها بأعلم من السائل ولكن سأحدثك عن أشراطها ، إذا ولدت الأمة ربتها
It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that: The Messenger of Allah (peace be upon him) was once present among the people when a man came and asked: O Messenger of Allah! When will the Day of Judgment come? He (peace be upon him) said: The one who is asked does not know more than the one who asks, but I will tell you some signs of the occurrence of the Day of Judgment: When a female slave gives birth to her mistress. (Then the Day of Judgment will be near)
Reference: Bukhari: Book of Faith: Chapter on Gabriel's Questioning the Prophet about Faith, Islam, and Excellence (50) Muslim (93) Ahmad (520/2 - 56) Abu Dawood (4696) Tirmidhi (2610) Nasa'i (5001) Ibn Majah (51) Ibn Hibban (173) Tayalisi (21) Shu'ab al-Iman (3973)
عن أبى هريرة رضى الله عنه قال كان رسول الله صلى الله عليه وسلم يوما بارزا للناس فأتاه رجل فقال ... إذا ولدت الأمة ربها
It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that one day the Messenger of Allah (peace be upon him) was present among the people when a man came and said... (then the Prophet (peace be upon him) said) When a female slave gives birth to her master, this is among the signs of the Day of Judgment.
Reference: Ahmad (178/4)
Benefits:
➊ A slave girl giving birth to her master is a sign of the Day of Judgment.
➋ Some narrations mention the master, and some mention the mistress, but the meaning is the same in both.
➌ The slave girl will give birth to her master; several interpretations of this have been transmitted from commentators. For example:
◈ Islam will spread, and the polytheists will be overcome, and their women will be made slave girls, from whom children will be born who will be the masters of the slave girls because those children are from the sperm of the slave girls' masters.
Reference: Ma'alim al-Sunan (677) Fath al-Bari (122/1) Sharh Nawawi (158/1)
◈ Hafiz Ibn Kathir (may Allah have mercy on him) and Hafiz Ibn Hajar (may Allah have mercy on him) consider this interpretation far-fetched and say that there is insight in this statement because when this prediction was made, the mentioned situation existed, whereas the Prophet Muhammad’s (peace be upon him) meaning is some situation that did not exist at that time but will occur near the Day of Judgment.
◈ There will be many wars, and there will be many slave girls. Slave girls will be bought and sold in abundance, while the children will belong to the masters. Then those same children will buy their own mothers as slave girls, but the children and the mothers will not be aware of the reality of the situation.
◈ The meaning of the slave girl becoming the master is that the children will not obey the mother but will treat the mother like a slave girl with disobedience. Although disobedience to mothers was also present during the time of the Prophet Muhammad (peace be upon him), which he forbade.
Dominant Meaning:
This sentence should be understood as a fact that, in reality, the slave woman will give birth to her master, and in today's scientific era, all this has been proven. People obtain a woman on rent and place their seed in her womb; then the child is nurtured in that woman's womb and is born, even though the woman is in the position of a servant (maid), while the one born is the master's child and, therefore, also the owner of the woman.