That he heard 'Umar bin Al-Khattab saying: "I heard the Messenger of Allah (ﷺ) saying: 'The martyrs are four: A believing man whose faith is good, he meets the enemy and proves faithful to Allah until he is killed. That is the one to whom the people will raise up their eyes like this on the Day of Judgement' and he raised his head until his Qalansuwah fell - I do not know if it was 'Umar's Qalansuwah or the Qalansuwah of the Prophet (ﷺ) that fell - he said, 'And a believing man whose faith is good (but not as brave as first), he meets the enemy, but due to cowardice, it only appears that he was struck with a thorn of an acacia tree when an unexpected arrow comes to him, yet it kills him. He is among the second level. And a believing man who has mixed righteous deed with another evil one, he meets his enemy and proves faithful to Allah until he is killed. This one is in the third level. And a believing man who wasted himself (in wrongdoing), he meets the enemy and proves faithful to Allah until he is killed. This one is in the fourth level.'"
This Hadith is Hasan Gharib, it is not known except as a narration of 'Ata bin Dinar.
He said: I heard Muhammad saying: "Sa'eed bin Abi Ayyub reported this Hadith from 'Ata bin Dinar - from some Shaikhs of Khawlan - and he did not mention 'from Abu Yazid' in it." And he said: "'Ata bin Dinar; there is no harm in him."
Jami` at-Tirmidhi Book 22, Hadith 27
Regarding His (Allah's) Statement:-- 'Move not your tongue concerning (the Quran) 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 Quran) 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 Quran) 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