You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Islamism

Context:
Some elements of the Brotherhood, though perhaps against orders, did engage in violence against the government, and its founder Al-Banna was assassinated in 1949 in retaliation for the assassination of Egypt's premier Mahmud Fami Naqrashi three months earlier. The Brotherhood has suffered periodic repression in Egypt and has been banned several times, in 1948 and several years later following confrontations with Egyptian president Gamal Abdul Nasser, who jailed thousands of members for several years.

Question:
Who was Al-Banna's assassination a retaliation for the prior assassination of?

Egypt's premier Mahmud Fami Naqrashi