How sound is the story of my deceased sister, whose grave was found burning with fire due to her negligence in prayer, and can human beings be privy to the torment of the grave?

Imam Al-Dhahabi mentioned the story of the punishment of the one who abandons prayer in the grave without a chain of narration (sanad), and many such narrations concerning encouragement and warning are weak or fabricated. The authentic verses and hadiths suffice regarding the torment of the grave and the warning against abandoning prayer, as well as describing the one who abandons prayer as an unbeliever and condemning him to Saqar (Hellfire). It is also mentioned in Sahih Ibn Hibban, and graded as hasan (good) by Al-Albani, what disobedient people are punished with in their graves, and that the one who observes prayer has the torment averted from him. It must be noted that one should not rely on the images of those being tormented in graves circulated online, as they are unproven and contradict the hadith in Sahih Muslim: "Were it not that you would not bury each other, I would have supplicated to Allah to let you hear the torment of the grave."