John Gill 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
Of the night, that is, after nine o'clock, or any time between nine or twelve; for the second watch was from nine o'clock till twelve; and this was coming early from an entertainment, or a wedding, which were commonly kept in the night, and late;

or come in the third watch ,
or after twelve o'clock, or any time between twelve and three; for the third watch was from twelve o'clock to three, which was late; (See Gill on Matthew 14:25) The Persic version reads, "in the second, or third part of the night"; and the Ethiopic version, "in the second or third hour of the night";

and find them so .
The Arabic version adds, "doing"; as above described, with their loins girt, lights burning, and they watching for their Lord's coming:

blessed are those servants ;
since they shall be used and treated as before related.