«فَسَجَدَ الْمَلَائِكَةُ كُلُّهُمْ أَجْمَعُونَ»
So the angels prostrated, all of them together.
The emphatic wording “all of them, together” removes a possible reading that excludes some angels. This illustrates the textbook's discussion of mufassar: when wording itself decisively clarifies what might otherwise be open to interpretation, it should not be treated as merely vague language.