Musannaf Ibn Abi Shayba 3:6009

Narrated to us Umar ibn Harun, from Ibn Jurayj, from Ata, regarding a man who had a nosebleed and it would not stop until he feared missing the prayer. He said: "He should plug his nostrils with a cloth and hasten to pray." I said: "Then it will enter his interior (stomach/throat)." He said: "Even if it does."