Fasting in Sha'ban is recommended; as narrated by Aisha (may Allah be pleased with her), she said: "The Messenger of Allah (peace be upon him) used to fast until we would say he does not break his fast, and he would break his fast until we would say he does not fast. I never saw the Messenger of Allah (peace be upon him) complete the fasting of any month except Ramadan, and I never saw him fasting more than he did in Sha'ban." This is in Sahih Bukhari, 7:6, and Sahih Muslim 3:223.