When a Mu'min (Muslim) in grave will answer correctly to the angle's questions
then he will be told to sleep like a groom sleeps and a window of Paradise
will be open for him. The question is that when a Mu'min will correctly
answer the questions, then from those who will be sinners, how will they
be punished in the grave?
A: Not every sinner will be freed from the Punishment of the Grave after answering the questions of the angles rather Allah will forgive whoever HE wants to and will punish whoever HE wants to, according to their sins. Faqih-e-Azam, Sayeduna Sadrus-Shari'ah (Alai Rahmatur Ridwan) writes that (After answering correctly), a caller will give a call from the sky that, "My servant has said the truth. Open a door for him towards paradise. He will be told to sleep like a groom sleeps". This (mentioned above) is common for the special people and among for common people whoever Allah wants and there will be punishment for some sinners according to their sins. Then because of his Peeran-e-Izam's or Imam's of the Madhab and Awliya's (Friends of Allah) intercede for him or simply just because of Allah's blessing they will be liberated. - (Bahar-e-Shaira'at, Vol. 1, Page 26 with reference to Nibras p 316) --- Allah Ta'ala Knows the best.