What is the Hadith that speaks of "the beardless youth," what is its meaning, what are the doubts raised concerning it, and how can they be refuted?

The People of the Sunnah deny any resemblance of Allah to His creation, believing that whoever likens Allah to His creation has committed an act of disbelief. They also hold that whatever Allah has described Himself with, or His Messenger has described Him with, is not a resemblance. Seeing Allah in a dream in different forms, such as a beardless youth, can occur, but it is a dream vision and does not mean that Allah the Almighty is truly in that form, for Allah does not resemble His creation. Some scholars have authenticated the hadith about the Prophet seeing his Lord in a dream in the form of a beardless youth, while others have weakened it, with the emphasis that it is a dream vision. It is not permissible for a Muslim to look into the doubts of the people of innovation unless he is qualified to refute them.