Tirmidhi

Hadith Commentary: Benefits and Issues:
This hadith is correct in terms of the actual matter and the reality of the event.
Imam Muslim rahimahullah himself has narrated this hadith.
And the correct meaning of this hadith is:
That to seek to kill a Muslim without a legitimate (shar‘i) necessity
is not the way of a Muslim,
therefore, such a person departs from our path and way.
But it does not mean what the Mu‘tazilah say:
that from this hadith it is understood
that one who commits a major sin (kabirah) leaves the fold of faith (iman),
even though he does not become a disbeliever (kafir),
but, like the disbelievers, will remain in Hellfire forever.
Whereas the actual reality is that a Muslim who commits a major sin
is a sinful and disobedient Muslim (fasiq and sinner),
the meaning of Muslim is:
one who obeys and submits,
and this person has departed from the way of obedience and submission of a Muslim,
therefore, due to being a criminal and sinner, if he does not repent,
or Allah ta‘ala does not forgive him out of His mercy,
then he is deserving of punishment, and after undergoing the punishment, or in the case of acceptance of intercession, he will come out of Hellfire through intercession.