How did the Prophet Muhammad, may Allah's peace and blessings be upon him, see the types of torment in the seven heavens before the Day of Resurrection and Reckoning?

Punishment in the grave is affirmed before the Day of Judgment, and it is not contingent upon it. Whoever deserves it will be punished therein, and then they will receive what has been decreed for them in the Hereafter. This is indicated by Allah’s statement concerning the people of Pharaoh: "The Fire, they are exposed to it morning and evening. And the Day the Hour appears [it will be said], 'Admit the people of Pharaoh to the severest punishment!'" (Ghafir: 46). It is also authentically reported in the Sahihayn (Bukhari and Muslim) that the Prophet, peace and blessings be upon him, passed by two graves whose occupants were being punished: one for not concealing himself from urine, and the other for spreading malicious gossip. In Bukhari, it is narrated that the disbeliever will be struck with iron hammers when he says, "I do not know." It should be known that the Messenger, peace and blessings be upon him, is truthful in everything he says, "Nor does he speak from [his own] inclination. It is not but a revelation revealed" (An-Najm: 3-4), and Allah informs him of whatever He wills from the unseen.