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 sleepsitting and then would pray without doing wudu. Translation Not Available

Book Ref: Muwatta Imam Malik Book 2 Hadith 41
Web Ref:  Muwatta Imam Malik Book 2 Hadith 10