Charles Ellicott Commentary Luke 12:38

"And if he shall come in the second watch, and if in the third, and find [them] so blessed are those [servants]." — Luke 12:38 (ASV)

And if he shall come in the second watch.—In Mark 13:35 we have the Roman four-fold division of the night. (See Note there.) Here we find the older Jewish division into three watches. (Judges 7:19, 1 Samuel 11:11).