Reward For Those Who Obey Allah And The Messenger (peace be upon him)

[وَمَن يُطِعِ اللَّهَ وَالرَّسُولَ فَأُوْلَـئِكَ مَعَ الَّذِينَ أَنْعَمَ اللَّهُ عَلَيْهِم مِّنَ النَّبِيِّينَ وَالصِّدِّيقِينَ وَالشُّهَدَآءِ وَالصَّـلِحِينَ وَحَسُنَ أُولَـئِكَ رَفِيقاً ]-Surah An-Nisa, Verse 69

Translation: And whoever obeys Allah and the Messenger, then they will be in the company of those on whom Allah has bestowed His grace, of the Prophets, the Siddiqin, the martyrs, and the righteous. And how excellent these companions are!
Reason Behind Revealing This Honorable Ayah/Verse
Ibn Jarir recorded that Sa`id bin Jubayr said, "An Ansari man came to the Messenger of Allah while feeling sad. The Prophet said to him, `Why do I see you sad' He said, `O Allah's Prophet! I was contemplating about something.' The Prophet said, `What is it' The Ansari said, `We come to you day and night, looking at your face and sitting by you. Tomorrow, you will be raised with the Prophets, and we will not be able to see you.' The Prophet did not say anything, but later Jibril came down to him with this Ayah,

[وَمَن يُطِعِ اللَّهَ وَالرَّسُولَ فَأُوْلَـئِكَ مَعَ الَّذِينَ أَنْعَمَ اللَّهُ عَلَيْهِم مِّنَ النَّبِيِّينَ]

(And whoever obeys Allah and the Messenger then they will be in the company of those on whom Allah has bestowed His grace, of the Prophets), and the Prophet sent the good news to the Ansari man.'' This Hadith was narrated in Mursal form from Masruq, `Ikrimah, `Amir Ash-Sha`bi, Qatadah and Ar-Rabi` bin Anas. This is the version with the best chain of narrators. Abu Bakr bin Marduwyah recorded it with a different chain from `A'ishah, who said; "A man came to the Prophet and said to him, `O Messenger of Allah! You are more beloved to me than myself, my family and children. Sometimes, when I am at home, I remember you, and I cannot wait until I come and look at you. When I contemplate about my death and your death, I know that you will be with the Prophets when you enter Paradise. I fear that I might not see you when I enter Paradise.' The Prophet did not answer him until the Ayah,

[وَمَن يُطِعِ اللَّهَ وَالرَّسُولَ فَأُوْلَـئِكَ مَعَ الَّذِينَ أَنْعَمَ اللَّهُ عَلَيْهِم مِّنَ النَّبِيِّينَ وَالصِّدِّيقِينَ وَالشُّهَدَآءِ وَالصَّـلِحِينَ وَحَسُنَ أُولَـئِكَ رَفِيقاً ]

(And whoever obeys Allah and the Messenger, then they will be in the company of those on whom Allah has bestowed His grace, of the Prophets, the true believers, the martyrs, and the righteous. And how excellent these companions are!) was revealed to him.'
**This is taken from Tafsir Ibn Kathir**