From Sahih Bukhari (Hadith 7531):
Narrated `Aisha:Whoever tells you that the Prophet (ﷺ) 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
Reference: Bukhari 7531