مُوَطَّأُ مَالِكٍ
Muwatta Malik 260
Tahajjud
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."
Arabic/English book reference: Book 7, Hadith 6