Albert Barnes Commentary Joshua 6:15

"And it came to pass on the seventh day, that they rose early at the dawning of the day, and compassed the city after the same manner seven times: only on the day they compassed the city seven times." — Joshua 6:15 (ASV)

On the seventh day - Most probably a Sabbath day. The rising early would be necessary to give time for encompassing the city seven times. Jericho appears to have been a city of considerable size and population; and each passage of the large host round it could hardly have taken less than an hour and a half. Thus, with the necessary intervals of rest, the evening would be at hand when Joshua gave the signal to shout (Joshua 6:16); and the work of slaughter was probably commenced just as the hours of the Sabbath were passed.