What is the ruling on a down payment when, for example, tailoring a garment?

There are two scenarios for tailoring a garment:

1. The raw material is provided by the customer, and the tailor is only responsible for the tailoring: This is considered an ijara (a contract of hire/service). In this case, selling the down payment (urboun) is permissible if the waiting period is specified for a defined duration. The urboun is counted as part of the price upon purchase, and it becomes the seller's right if the buyer reneges on the purchase.

2. The raw material is provided by the tailor, and the customer is required to pay for both the material and the tailoring: The ruling regarding the urboun here is the same as in the previous scenario.