{Were gathered together} (sun(8863)hth(8873)an). First aorist
(effective) passive indicative. The church is not named here as
in verse  4 , but we know from verses  12-22  that the whole
church came together this time also along with the apostles and
elders. {Of this matter} (peri tou logou toutou). Same idiom in
 8:21  19:38 . They realized the importance of the issue.