Muwatta Malik 1282
موطأ مالك#1282SahihThese are the words of a Successor — the generation after the Companions — not of the Prophet ﷺ.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ قَالَ سَمِعْتُ سَعِيدَ بْنَ الْمُسَيَّبِ، يَقُولُ لاَ رَضَاعَةَ إِلاَّ مَا كَانَ فِي الْمَهْدِ وَإِلاَّ مَا أَنْبَتَ اللَّحْمَ وَالدَّمَ .
Yahya related to me from Malik that Yahya ibn Said said that he heard Said ibn al-Musayyab say, "Suckling is only while the child is in the cradle. If not, it does not cause flesh and blood relations
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: 30:11