The part that involves drinking something:

Quote from harry potter:
Do you think the Horcrux is in there, sir?
Oh, yes.
It has to be drunk.
All of it has to be drunk.
You remember the conditions on which I brought you with me?
This potion might paralyze me.
Might make me forget why I'm here.
Might cause me so much pain that I beg for relief.
You are not to indulge these requests.
It's your job, Harry, to make sure I keep drinking this potion.
Even if you have to force it down my throat.
Understood?