This suggests they didn’t make those bits up.
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As is well known, the Easter narratives in the 4 gospels differ considerably.
-1st person(s) to tomb = female
-Tomb seen before Jesus
-Brightly clad being(s) met at tomb
But they differ on number of women, angels/men, sequence, positions, speech, etc.
That’s what makes their agreement in some small details more striking.
Narrators naturally have more freedom in choosing their own wording, than in truthfully reporting that of others.
Supposing gospel writers made up speech will not explain Matthew’s agreement with the other 3.
However, if they inherited tradition/memory their agreement is easily explained.
There are fewer simple ways to explain *agreements* in speech amid narrative differences.
One of the simplest is to attribute agreement to actual memory of speech.