Does blood coming out of the mouth due to using a siwak invalidate ablution, and is it permissible to swallow it during prayer?

Bleeding from the mouth does not invalidate ablution (Wudu'), even if the amount of blood is significant. However, it is impermissible to swallow it, whether during prayer or outside of it, due to the Almighty's saying: "Forbidden to you are carrion and blood." To dispose of the blood during prayer, one may spit it into a tissue. This is a minor movement that does not invalidate the prayer. The permissibility of this is supported by the action of Ibn Abi Awfa and by the Prophet's (peace be upon him) hadith concerning spitting during prayer. It is more cautious to dispose of the tissue after spitting into it.