Hadith 4:882
Ibn Numayr narrated to us, he said: Uthman ibn Hakim narrated to us, he said: I asked Sa'id ibn Jubayr about fasting in Rajab. He said: I heard Ibn Abbas saying: The Messenger of Allah, peace and blessings of Allah 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.
حدثنا بن نمير قال حدثنا عثمان بن حكيم قال سألت سعيد بن جبير عن صيام رجب فقال سمعت بن عباس يقول كان رسول الله صلى الله عليه وسلم يصوم حتى نقول لا يفطر ويفطر حتى نقول لا يصوم