“I wrote to the Imam (a.s.), may Allah take my soul in service for your cause, explain to me what is gain and profit? What is its limit? What is your opinion? May Allah grant you long life. I will be grateful for your explanation so I will not continue in unlawful activities with invalid prayer and fasting.” He wrote to me , “Gain and profit is the income from trade from its net profit or from farming after the deduction of expenses and prizes.”