ISB ~ Acts 3 v1

Peter and John:Closely associated in the writings of Luke (8:14; Lk 22:8) and John (Jn 18:15; 20:2-3; 21:20-23).

the hour of prayer:Twice a day liturgical services were held in the Temple, at the time of the morning and evening sacrifices (Ex 29:38-39). The ninth hour corresponds to the evening prayers recited around 3 P.M., just a few hours before sunset and the end of the Jewish day. See note on Lk 1:10.