A person in our street runs a Jewish bookstore from his house. A few months ago I asked him to order 2 copies of a sefer that I was planning to learn with my friend. The store owner took down my phone number and said he would call me when the books arrive. Meanwhile, my friend and I decided to learn something else so I no longer need the sefarim. He hasn’t rung yet and I think he may have forgotten. I don’t know if he actually ordered the books or whether they were delivered. Should I check with him and am I obligated to buy the books if they arrived?
If the books were ordered specifically for you, the general ruling is that you have an obligation to buy them (see below).
This is because the storekeeper is “motzi hoza’os al piv” – he spends money on your behalf, and because of your intention to buy the books.
You should call him and cancel the order, or ask him if he minds keeping the books since you no longer need them.
Note that if he insists that you buy the books, you don’t actually have to buy them, and it is sufficient that you pay his costs.