John 1:39

He saith unto them, Come and ye shall see. They came, therefore, and saw where he abode; and they abode with him that day: and it was about the tenth hour.

Jesus thus rewarded the two disciples by inviting them home with him, which resulted in their spending the whole day. From this statement, coupled with the information that it was about the tenth hour, it has been supposed that John was here using the Roman method of counting time, thus making it about 10:00 A.M. when this occurred. The Jews numbered the hours of the day from 6:00 A.M., and by their method of reckoning, the tenth hour would have been 4:00 P.M.; and it would appear inappropriate to refer to the time remaining as "that day." The significant thing to note in this place, however, is the fact that the author recalled so exactly the very hour of the day when these events took place. The reason for this was the fact that it was the very day and hour that brought him into the presence of the Holy One of God, a presence that changed John's life and changed the world. No wonder the events and words of that day were burned into his memory forever.