Musannaf Ibn Abi Shayba 3:6098

Abu Bakr narrated to us, he said: Hushaym narrated to us, from Yunus, from al-Hasan, he said: If he has a nosebleed after he finishes the final prostration, he should depart, perform ablution, and return to recite the tashahhud, as long as he has not spoken. If he has spoken, he must restart the prayer.