## In those days ##

"In those days shortly after Jesus went back to heaven"

## in the midst of the brothers ##

"brothers" often refers to fellow believers and would include both men and women.

## It was necessary that the scripture should be fulfilled ##

Peter is specifically addressing the prophecies that related to Judas.

## by the mouth of David ##

"the words of David." The word "mouth" is used to refer to "words" even though David wrote them. (See: [[rc://en/ta/man/translate/figs-metonymy]])