Wa Alaykum Assalam and thank you for your questions.

Obviously, slavery issues are no longer applicable at our time. Currently, Muslims may not enslave anyone because slavery has been abolished; not even enemies captured during wars.

The first hadith you referenced, captives of war are women of the enemy combatants; it is not surprising that they were already married but heir husbands died in war. So when Muslims, defeated the enemy at that time, the men were either killed or made prisoners of war, while the women were taken as captives and distributed among the men to take care of them.

Allah allowed the Muslims to sleep with those ladies, mainly to avoid any social corruption such as prostitution if left without supervision.

On the other hand, we must put things into perspective that in our modern civilized world, whenever Muslims were subjected to war such as in Bosnia and Iraq, thousands of Muslim girls and women were raped.

During the Bosnian war in the early nineties, more than fifty thousand Muslim ladies were imprisoned and raped. The count in Iraq is unknown but the same treatment was shown to Muslim women.

I challenge anyone to bring proofs throughout history that Muslims mistreated women during wars.

As for the second hadith, we don’t have further details regarding the reasons why Jarir killed his slave. It appears that he only did so because the slave ran away; there could have been other reasons.

I hope this helps answer your questions.

Salam and please keep in touch.