Muwatta Malik 259
موطأ مالك#259Da'ifThese are the words of a Successor — the generation after the Companions — not of the Prophet ﷺ.
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، كَانَ يَقُولُ يُكْرَهُ النَّوْمُ قَبْلَ الْعِشَاءِ وَالْحَدِيثُ بَعْدَهَا .
Yahya related to me from Malik that he had heard that Said ibn al-Musayyab used to say, "Sleep is disapproved of before isha and conversation after it
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:
Salim al-HilaliMaqtu Daif
In-book reference: 7:6