It is the Holy Qur'an which says it

We find in the Qur'an:

"Only those that have knowledge fear God"


and we find in the Qur'an:

"it is those that honor him (Muhammad, peace be upon him and his family), help him and follow the light which is sent down with him, it is these that will prosper"
(possibly a slightly different wording)


We find in the Qur'an:

"Muhammad is the Messenger of God"


We find in the Qur'an:

"He has sent down the balance"


We find in the Qur'an:

"O mankind fear your Lord"


We find in the Qur'an:
"those who believe in the revelation given to Muhammad"


We find in th Qur'an:
"The path of those You have favored"


We find in the Qur'an:
"Not those whose portion is wrath and not those who go astray"


In a famous Hadith, Muhammad called Ubayy Ibn Kaab to him, but Ubayy was praying so he did not respond. When he came after he finished his prayer, Muhammad rebuked him, asking him if he did not hear the verse "respond to the Messenger when he calls you to that which gives you life" (possibly a different wording).

In a famous Hadith Qudsi, God Almighty says, more or less: "When I love him, I will be his eyes with which he sees, his ears with which he hears, his hands with which he seizes (or strikes) and his feet (or legs) with which he walks"