Sahih Bukhari Volume 003, Book 031, Hadith Number 191.
Narated By 'Aisha : The Prophet never fasted in any month more than in the month of Sha'ban. He used to say, "Do those deeds which you can do easily, as Allah will not get tired (of giving rewards) till you get bored and tired (of performing religious deeds)." The most beloved prayer to the Prophet was the one that was done regularly (throughout the life) even if it were little. And whenever the Prophet offered a prayer he used to offer it regularly.