I asked Anas bin Malik about the recitation of the Prophet. He said, "He used to pray long (certain sounds) very much.
Sahih al-Bukhari Book 66, Hadith 69
← Previous Hadith Regarding His (Allah's) Statement:-- 'Move not your tongue concerning (the Qur'an) to make haste therewith.' (75.16) And whenever Gabriel descended to Allah's Messenger (ﷺ) with the Divine Inspiration, Allah's Messenger (ﷺ) used to move his tongue and lips, and that used to be hard for him, and one could easily recognize that he was being inspired Divinely. So Allah revealed the Verse which occurs in the Surah starting with "I do swear by the Day of Resurrection.' (75.1) i.e. 'Move not your tongue concerning (the Qur'an) to make haste then with. It is for Us to collect it (in your mind) (O Muhammad) an give you the ability to recite it 'by heart.' (75.16-17) which means: It is for us to collect it (in your mind) and give you the ability to recite it by heart. And when We have recited it to you (O Muhammad) through Gabriel then follow you its recital. (75.18) means: 'When We reveal it (the Qur'an) to you, Listen to it.' for then: It is for Us to explain it and make it clear to you' (75.19) i.e. It is up to Us to explain it through your tongue. So, when Gabriel came to him, Allah's Messenger (ﷺ) would listen to him attentively, and as soon as Gabriel left, he would recite the Revelations, as Allah had promised him.

Sahih al-Bukhari Book 66, Hadith 68 Next Hadith → Anas was asked, "How was the recitation (of the Qur'an) of the Prophet?' He replied, "It was characterized by the prolongation of certain sounds." He then recited: In the Name of Allah, the Most Beneficent, the Most Merciful prolonging the pronunciation of 'In the Name of Allah, 'the most Beneficent,' and 'the Most Merciful.

Sahih al-Bukhari Book 66, Hadith 70