Maliks Muwatta Book 2, Hadith Number 21.
Section : Discontinuing Doing Wudu on Account of Eating Cooked Food.
Yahya related to me from Malik that both Muhammad ibn al-Munkadir and Safwan ibn Sulaym transmitted to him from Muhammad ibn Ibrahim ibn al-Harith at-Taymi from Rabia ibn Abdullah ibn al-Hudayr that he had eaten an evening meal with Umar ibn al-Khattab who then prayed without doing wudu.