Is it permissible for a Muslim to donate blood, and is their prayer valid immediately after donating?

It is permissible to donate blood when necessary, based on Allah's saying: "And whoever saves a life - it is as though he had saved all mankind" [Quran 5:32], and "But whoever is forced [by necessity], neither desiring [it] nor transgressing [its limit], there is no sin upon him" [Quran 2:173]. Scholars have differed on whether the emission of blood invalidates wudu (ablution). The preponderant opinion is that the emission of blood does not invalidate wudu, although performing wudu after it is recommended.