what is the glass bottle for? (The Witcher)

I found a "glass vial" in the outskirts in the crypt near the dead girl Ilsa and when I picked it up it rushed to the inventory section "for tasks" what to do with it ???
Talk to Mikula...

slesher13
This is a quest item, do as Sveige said.... .

I completed this mission six times and without a bottle, I approached Mikula, and the bottle remained in inventory. He needs something else.

on the head to whom the thread is fucking

In my opinion, we learn about the fact that Ilsa was raped not because of the bottle, but there in the dialogue it means! no need.

The only thing you can do with this vial is to give it to the Reverend at the end of the first chapter (if you burn Abigail). And that, in fact, will not give anything.

He will disappear anyway at the end of the chapter, just forgot about it.

Sveige hmm, strange... And I kept it in my inventory until the end of the game.

Now I started replaying the first Witcher, and this question also arose. From what I understand, picking up the vial causes additional phrases to appear when talking to the Reverend when they want to burn Abigail.