Muwatta Malik 1112
موطأ مالك#1112SahihThese are the words of a Successor — the generation after the Companions — not of the Prophet ﷺ.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّهُ كَانَ يَقُولُ يُنْهَى أَنْ تُنْكَحَ الْمَرْأَةُ عَلَى عَمَّتِهَا أَوْ عَلَى خَالَتِهَا وَأَنْ يَطَأَ الرَّجُلُ وَلِيدَةً وَفِي بَطْنِهَا جَنِينٌ لِغَيْرِهِ .
Yahya related to me from Malik from Yahya ibn Said that Said ibn al-Musayyab said, "It is forbidden to be married to a woman and her paternal or maternal aunt at the same time, and for a man to have intercourse with a female slave who is carrying another man's child
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 28:22