Question 131: A Muslim man said to his brother in Islaam: “You are a disbeliever,” though the accused person performs the five obligatory prayers and observes Sawm (fast). What is the ruling in this regard? Also, what is the remedy for continuous forgetfulness?
Answer: It is not permissible for a Muslim to accuse his brother in Islaam of disbelief, if he is not so. He should repent to Allaah and seek his forgiveness from this sin. Moreover, he has to ask the accused person to pardon him. The Prophet (peace be upon him) forbade this in many authentic Hadeeths. As to the remedy of forgetfulness and the slowness of memorization, you have to fear Allaah (Glorified and Exalted be He), continue studying and repeating what you memorize and ask Allaah to support you with that. We ask Allaah to grant us all success in achieving what we want…. read more here.