John 11:9

Twelve hours. The Jewish day was reckoned from sunrise to sunset and was divided into twelve parts. As the length of the day varied with the seasons, from about 14 hours and 12 minutes at the time of the summer solstice to about 10 hours and 3 minutes at the time of the winter solstice, so the length of the hour varied. The maximum variation in the length of an hour was some 20 minutes.

Walk in the day. Compare the thought in vs. 9, 10 with that expressed in ch. 9:4 (see comment there). There the emphasis is on the thought of labor while opportunity lasts; here on the fact that Jesus’ hour had not yet come (see on ch. 7:6).