What constitutes apostasy
The matters which constitute apostasy are divided into four categories:
(a)Apostasy in beliefs,such as associating others with Allah, denying Him, or denying an attribute which is proven to be one of His attributes, orby affirming that Allah has a son.

Whoever believes that is an apostate and a disbeliever.
(b)Apostasy in words, such as insulting Allah or the Messenger (peace and blessings of Allah be upon him). (c)Apostasy in actions, such as throwing the Qur’an into a filthy place, because doing that shows disrespect towards

the words of Allaah, so it is a sign that one does not believe. Other such actions include prostrating to an idol or to the sun or moon.
(d)Apostasy by omission, such as not doing any of the rituals of Islam, or turning away from following it altogether.

What is the ruling on the apostate?
If a Muslim apostatizes and meets the conditions of apostasy – i.e., he is of sound mind, an adult and does that of his own free will – then his blood may be shed with impunity. He is to be executed by the Muslim ruler or by his deputy –

such as the qaadi or judge, and he is not to not be washed (after death, in preparation for burial), the funeral prayer is not to be offered for him and he is not to be buried with the Muslims.
The evidence that the apostate is to be executed is the words of the Prophet (SAW):

“Whoever changes his religion, execute him.” (Narrated by al-Bukhaari, 2794). What is meant by religion here is Islam (i.e., whoever changes from Islam to another religion).

The Prophet (peace and blessings of Allaah be upon him) said:

“It is not permissible to shed the blood of a Muslim who bears witness that there is no god except Allaah and that I am His Messenger, except in one of three cases: a soul for a soul (i.e., in the case of murder); a married man who commits adultery; #SaveKanoNine

and one who leaves his religion and splits form the jamaa’ah (main group of Muslims).” (Narrated by al-Bukhaari, 6878; Muslim, 1676)
See al-Mawsoo’ah al-Fiqhiyyah, 22/180.
Thus it will be clear to you that execution of the apostate is something that is commanded by Allaah,

when he commanded us to obey the Messenger (peace and blessings of Allaah be upon him), as He says (interpretation of the meaning):
“O you who believe! Obey Allaah and obey the Messenger (Muhammad), and those of you (Muslims) who are in authority”

[al-Nisa’ 4:59] #BBNaija