2 Nephi 9:41-42.

“…Behold, the way for man is narrow, but it lieth in a straight course before him, and the keeper of the gate is the Holy One of Israel; and he employeth no servant there; and there is none other way save it be by the gate; for he cannot be deceived, for the Lord God is his name.⁴² And whoso knocketh, to him will he open; and the wise, and the learned, and they that are rich, who are puffed up because of their learning, and their wisdom, and their riches–yea, they are they whom he despiseth; and save they shall cast these things away, and consider themselves fools before God, and come down in the depths of humility, he will not open unto them.”

Cf. “The Keeper of the Gate” and “Temple Motifs in Jewish Mysticism” under Temple and Other Religions as well as Brown, Symbols in Stone, 130-131.

There is much more to be said about this. A longish essay will be added to the Temple Preparation section about it.