He says the killer of a Companion is a disbeliever. No, it is not absolute that whoever kills a Companion is a disbeliever.

But whoever considers it permissible to kill a Muslim, whether he is a Companion or not, whoever says killing a Muslim is halal, he is a disbeliever.

So, who says this? That is, he makes permissible what Allah has forbidden. Allah, the Exalted, has made killing a Muslim haram, and this person says killing a Muslim is halal.

This is someone who opposes Allah, this is a disbeliever, whether the one killed is a Companion or not.

As for someone who killed a Companion, we look at the situation here.

The killer may be a disbeliever, as in battles between Muslims and disbelievers.

So this disbeliever kills the Companion, he is originally a disbeliever and then he becomes Muslim.

If this disbeliever becomes Muslim after that, then his Islam benefits him. Likewise, if there is a fitna as happened in Siffin.

There was fighting among the sahaba in the Battle of the Camel, there was fighting among the sahaba, so it is not said here.

That he is a disbeliever, the Companion who killed the Companion or so on, this was a fitna that happened among us, and it was fighting over the religion, each one thought the other was mistaken, so it is not said here that he is

a disbeliever. As for Abu Lu'lu'a the Magian, you said Abu Lu'lu'a is a Magian, and he was not a Muslim in the first place, nor did he become Muslim, nor did he enter Islam.

He was originally a Magian and died as a Magian, and he killed Umar ibn al-Khattab, may Allah be pleased with him.

As for Yazid, Yazid did not kill al-Husayn.

may Allah be pleased with him, nor did he order his killing. Yazid, it was the Shia who killed Husayn when they told him: come, then they turned against him and killed him.

And not Yazid, he had nothing to do with this. But there is no doubt that the killing of al-Husayn was a tremendous calamity, and whoever considers the killing of al-Husayn permissible is certainly a disbeliever, whoever says that killing al-Husayn is allowed.

This is a disbeliever, and we seek refuge with Allah.