Muwatta Malik
Purity
Hadith #9
2.9
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ ابْنَ عُمَرَ، كَانَ يَنَامُ جَالِسًا ثُمَّ يُصَلِّي وَلاَ يَتَوَضَّأُ .
Yahya related to me from Malik from Nafithat Ibn Umar used to sleep sitting and then would pray without doing wudu