Is it permissible for a lawyer to take his fee – 300 pounds – in addition to one-tenth of the amount recovered if he wins the case?

The majority of scholars hold that it is impermissible to combine a known amount with a percentage of the حاصل (proceeds/earnings) as a wage, due to the presence of jahalah (uncertainty). They stipulate that the wage must be a known amount to prevent disputes. However, some scholars permit this.