Is it permissible to pay a deposit ranging from 20-50% for online purchases, with the remaining amount to be paid in cash upon delivery, in order to ensure product quality given the impossibility of prior viewing?

It is permissible to buy dates, raisins, or almonds by description in various scenarios:

1. If the commodity is not available with the seller, then a Salam sale is valid, provided it is described accurately, the delivery date is specified, and the full price is paid at the time of the contract.

2. If the commodity is available with the seller but absent from the buyer:

If the quantity is specified and determined, and cannot be substituted, it is permissible to pay a portion of the price and defer the remainder.

If the quantity is not specified but only described (a sale of something described but owed in liability), then the full price must be paid at the time of the contract, and this is usually the case.

3. The purchase can take place upon delivery, and what precedes it is a promise. The buyer does not pay anything with this promise unless it is a "serious deposit" from which the seller does not benefit. It is not permissible to combine a loan and a sale.