Hadith 4:893
Waki' narrated to us, from Sufyan, from Zayd ibn Aslam, who said: The Messenger of Allah (may Allah bless him and grant him peace) was asked about fasting in Rajab, and he said: "Where are you regarding Sha'ban?"
حدثنا وكيع عن سفيان عن زيد بن أسلم قال سئل رسول الله صلى الله عليه وسلم عن صوم رجب فقال أين أنتم من شعبان