Muwatta Malik 38
موطأ مالك#38Da'ifوَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، قَالَ إِذَا نَامَ أَحَدُكُمْ مُضْطَجِعًا فَلْيَتَوَضَّأْ .
Yahya related to me from Malik from Zayd ibn Aslam that Umar ibn al-Khattab said, "If you fall asleep Iying down you must do wudu ( before you pray)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Daif
In-book reference: 2:7