Praise be to Allah.
We put the following question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen:
A shopkeeper doing business in the West has Christians who come in, drunk or staggering, to buy things that are permissible. Is it permissible for him to sell to them?
He replied, may Allaah preserve him:
Yes, so long as they are Christian.
It is permissible because the Christians believe that it is permissible to drink alcohol.
The question in our minds is that one of the two parties [engaged in the transaction] is not in his right mind.
Does he not know how to make a purchase?
There are different types of drunkenness: a person may or may not be aware that he is buying something.
If they are in such a state that they do not know (what they are doing), then it is not permissible to deal with them.
But if he is drunk and does know what he is doing?
Then there is nothing wrong with it, as it says in the aayah (interpretation of the meaning):
“Approach not As-Salaah (the prayer) when you are in a drunken state until you know (the meaning) of what you utter” [al-Nisaa’ 4:43]
And Allaah knows best.