1- I am a wholesaler and sometimes buy goods on credit without receiving an invoice with the prices (because they are more or less known). Then I sell the goods to a vendor at a specific price while being unaware of the exact capital value of the goods. Is that sale permissible?
2- I sell goods to certain vendors on credit and they usually take the goods without naming the price at the same time (because they are more or less known). A few days later, they come to me and get invoices with the items and their prices. Is that sale permissible?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

Among the conditions of the validity of a sale is that both the price and commodity should be known beyond gross ignorance that would lead to disputes and quarrels. In case of slight ignorance that does not lead to dispute, the sale is valid.

Consequently, if the price is more or less known to the contractors and a potential increase or decrease in the price would not really lead to disputes, then it is permissible not to specify the price at the time of contracting, especially when this is necessary. However, it is preferable to determine the price for fear of potential disputes.

Allaah Knows best.