Sahih Bukhari
Prophetic Commentary on the Quran (Tafseer of the Prophet (PBUH))
Volume: 006 / Book Number: 060 / Hadith Number: 136
Narrated 'Aisha:
Whoever tells that Muhammad concealed part of what was revealed to him, is a liar, for Allah says:--
"O Apostle (Muhammad)! Proclaim (the Message) which has been sent down to you from your Lord." (5.67)