How sound is the Hadith: "It is from the Sunnah to walk forty steps after eating"? And what was the habit of the Messenger of Allah, peace and blessings be upon him, regarding food and drink? Did he drink before or after eating? Did he walk or not? And what was his eating like in general?

Walking after eating is not from the words of the Prophet, peace and blessings be upon him. Rather, Ibn al-Qayyim mentioned it as coming from the Arab physician Al-Harith bin Kaladah, who advised that one who has eaten dinner should walk forty steps. As for the Messenger's habit of drinking, it was not his guidance to drink with his food, thereby spoiling it, especially if the water was hot or cold. It is disliked to drink water immediately after exercise, fatigue, intercourse, eating, before eating, after eating fruit, after bathing, and upon waking from sleep; all of this contradicts the preservation of health.