Is repentance from the utterance of disbelief spoken in a moment of anger a condition for returning to Islam, and is prayer accepted before returning to Islam, based on the condition of "Islam" for the validity of prayer?

The repentance of an apostate is by uttering the Two Testimonies (Shahadatayn) and regretting the sin. Repentance is valid if regret and the utterance of the Two Testimonies are present. Prayer is also considered an act of embracing Islam, and if a Muslim performs even one unit (rak'ah) of prayer, it brings him into Islam, because it is a pillar specific to Islam. Ghusl (ritual bathing) is not required after repentance from apostasy unless the apostate committed an act during his apostasy that necessitated ghusl.