Musannaf Ibn Abi Shayba 36:533

Abu Usama narrated to us, from Hisham ibn Urwah, from his father, from Sulayman ibn Yasar, from al-Miswar ibn Makhrama, who said: I and Ibn Abbas entered upon Umar after he had been stabbed, and he had fainted. We said, "He will not wake up for anything more important to him than the prayer." So we said, "The prayer, O Commander of the Faithful." He woke up and said, "There is no share in Islam for a person who abandons the prayer." So he prayed, while his wound was gushing blood.