Assalaamu ‘alaykum,When one buys a lot of goods from for example the supermarket is it mandatory that the price of each product has to be known in order for the transaction to be valid. Usually when going to the supermarket, I don’t check the prices of each product that I am planning to buy, I just pay the total price of all the goods.
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
You do not have to verify the price of each commodity when buying; it is sufficient for you to know the total price of the purchased commodities.
Fath al-‘Ali Al-Maalik fi al-Fatwa ‘ala Math-hab al-Imam Maalik reads:
“What is your view about what takes place in rural countries when a man sells a cow with its offspring, or a sheep with its offspring, and the price for each of them is not specified. So, if one of the sellers wants to invalidate the sale because of that, has he the right to do so or not. I (i.e. ‘Illeech) replied: ‘All perfect praise be to Allah and may the Blessings and Peace of Allah be upon the Prophet: Yes, he has no right to do so [to invalidate the sale] because the price as well as the commodity are not unknown in general and in details, because the buyer and the seller know the price, and the commodity is the cow and its offspring, for example, and this does not contradict the lack of details for each of them [the animals].” [End of quote]
Since the sale is permissible while the seller and the buyer do not know the exact details of the price of sale [of each item], then it is more appropriate that the sale is valid when the seller knows the details.
Allah knows best.
You can search for fatwa through many choices