A Hadees which proves The Aqeedah of Ahlus Sunnah. 

Narrated Ibn `Abbas رَضِيَ اللهُ عَنْهُ :
Once the Noble Prophet ﷺ , while passing through one of the graveyards of Medina or Mecca heard the voices of two persons who were being tortured in their graves. The Noble Prophet ﷺ said, "These two persons are being tortured not for a major sin (to avoid)." The Noble Prophet ﷺ then added, "Yes! (they are being tortured for a major sin). Indeed, one of them never saved himself from being soiled with his urine while the other used to go about with calumnies (to make enmity between friends). The Noble Prophet ﷺ  then asked for a green leaf of a date-palm tree, broke it into two pieces and put one on each grave. On being asked why he had done so, He (ﷺ) replied, "I hope that their torture might be lessened, till these get dried."

Sahih al-Bukhari 216

Points that can be understood from the above Hadees.

1. The dead are actually alive in Barzakh and feel the punishments as well. If not there is no meaning of comfort and discomfort in Grave.

2. The dead can also talk but everyone is not able to listen except the Chosen Ones.

3. Punishment of the people in Barzakh is not hidden from The Most Beloved ﷺ

4. As per the narrations, human being and jinn cannot hear the voice of a person having Azaab, but The Pious can hear cleary.

5. The sins of the people, even a bit are not hidden from the blessed sight of the Most Beloved ﷺ

6. The most Beloved ﷺ is aware of the punishments and the reason for the punishments as well.

7. The Most beloved ﷺ is Rahmat even for the dead.

8. The most beloved ﷺ gives comfort to the dead by His Rahmat. 

9. The Tasbeeh of the leaves is also heard by the Most Beloved ﷺ.

10. The Trees and the leaves are bound to obey the command of Nabi e Kareem ﷺ

11. The Zikr of Allah is a mean for the lessening of Azaab.

12. The Qur'an is also a Zikr of Allah, thus reciting Surah Yaseen, Surah Fatiha, or The whole Qur'an for the dead is a mean for Rahmat.

Only an ignorant will deny the above facts.