Sahih Bukhari | Volume 9 | Hadith Number 622

Narrated by 'Aisha
Whoever tells you that the Prophet concealed something of the Divine Inspiration, do not believe him, for Allah said: 'O Apostle Muhammad! Proclaim (the Message) which has

been sent down to you from your Lord, and if you do it not, then you have not conveyed His Message.' (5:67)