Allah Most High’s words:

“It is for Us to gather it and recite it.
So when We have recited it, follow its recitation.
Then it is for Us to explain it.”

are like His words:

“We recount to you in truth some of the story of Moses and Pharaoh,”

and His words:

“We relate to you the best of stories through Our revelation of this Quran to you,”

and similar passages concerning what the Lord does through His angels. The word “We” is used for one who commands obedience and has helpers who obey him. The Lord Most High created the angels and all other beings; the angels obey Him far more fully than a created being obeys his helpers. Thus He, glorified be He, has a greater right than anyone else to such expressions as “We,” “We did,” and the like.

In the two Sahīh collections, Ibn ʿAbbās said:

“The Prophet, may Allah bless him and grant him peace, experienced great hardship when receiving revelation and would move his lips.”

Ibn ʿAbbās said: “I shall move them for you as the Messenger of Allah, may Allah bless him and grant him peace, used to move them.”

Saʿīd ibn Jubayr said: “I shall move them as I saw Ibn ʿAbbās move them.” He then moved his lips.

Then Allah revealed:

“Do not move your tongue with it to hasten it.
It is for Us to gather it and recite it.”

He explained: “To gather it in your heart for you, so that you may recite it.”

“So when We have recited it, follow its recitation.”

“When Our messenger recites it”—or, in another wording, “when Gabriel recites it”—“listen to him and remain silent.”

“Then it is for Us to explain it.”

“That is, We shall recite it.”

After that, whenever Gabriel came to the Messenger of Allah, may Allah bless him and grant him peace, he would listen. Once Gabriel had departed, the Prophet, may Allah bless him and grant him peace, would recite it just as Gabriel had recited it.