Allah addresses His servant and Messenger Muhammad by the title 'Messenger' and commands him to convey all that He has sent him, a command that the Prophet has fulfilled in the best manner.
Al-Bukhari recorded that 'A'ishah said, "Whoever says to you that Muhammad hid any part of what Allah revealed to him, then he is uttering a lie. Allah said,
{O Messenger! Convey what has been sent down to you from your Lord.}

Al-Bukhari collected the short form of this story here, but mentioned the full narration in another part of his book. Muslim in the Book of Iman, At-Tirmidhi, and An-Nasa'i in the Book of Tafsir of their Sunans also collected this Hadith.
In is recorded in the Two Sahihs that 'A'ishah said, "If Muhammad hid anything from the Qur'an, he would have hidden this Ayah,
{But you did hide in yourself that which Allah will make manifest, you did fear the people while Allah had a better right that you should fear Him.}"
Al-Bukhari recorded that Az-Zuhri said, "From Allah comes the Message, for the Messenger is its deliverance and for us is submission to it." The Ummah of Muhammad has testified that he has delivered the Message and fulfilled the trust, when he asked them during the biggest gathering in his speech during the Farewell Hajj. At that time, there were over forty thousand of his Companions. Muslim recorded that Jabir bin 'Abdullah said that the Messenger of Allah said in his speech on that day,
"O people! You shall be asked about me, so what are you going to reply?"
They said, "We bear witness that you have conveyed (the Message), fulfilled (the trust) and offered sincere advice." The Prophet kept raising his finger towards the sky and then pointing at them, saying,
"O Allah! Did I convey? O Allah! Did I convey?"
Allah's statement,
{And if you do not, then you have not conveyed His Message.}

meaning: If you do not convey to the people what I sent to you, then you have not conveyed My Message. Meaning, the Prophet knows the consequences of this failure. 'Ali bin Abi Talhah reported that Ibn 'Abbas commented on the Ayah,
{And if you do not, then you have not conveyed His Message.}

"It means, if you hide only one Ayah that was revealed to you from your Lord, then you have not conveyed His Message."
Allah's statement,
{Allah will protect you from mankind} means, you convey My Message and I will protect, aid and support you over your enemies and will grant you victory over them. Therefore, do not have any fear or sadness, for none of them will be able to touch you with harm. Before this Ayah was revealed, the Prophet was being guarded, as Imam Ahmad recorded that 'A'ishah said that the Prophet was vigilant one night when she was next to him; she asked him, "What is the matter, O Allah's Messenger?" He said,
"Would that a pious man from my companions guard me tonight."
She said, "Suddenly we heard the clatter of arms. The Prophet said,
'Who is that?'"
He (the new comer) replied, "I am Sa'd bin Malik (Sa'd bin Abi Waqqas)." The Prophet asked,
"What brought you here?"
He said, "I have come to guard you, O Allah's Messenger."
{wills,} and,
{Your duty is only to convey and on Us is the reckoning.}