John Gill Commentary Luke 12:46

"the lord of that servant shall come in a day when he expecteth not, and in an hour when he knoweth not, and shall cut him asunder, and appoint his portion with the unfaithful." — Luke 12:46 (ASV)

The Lord of that servant will come in a day when he
looks not for him
For, not coming as was expected, he gives over looking, and concludes he will not come at all; in which he will find himself mistaken, for he will come in the very day which is appointed, though men know not of it, and do not look for it:

and at an hour when he is not aware ;
for as neither the day, nor hour of Christ's coming are known to any man, it becomes men to look for it every day and hour, lest it come upon them unawares; as it will, on such evil servants before described, with whom it will go ill, as follows:

and will cut him in sunder, and appoint him his portion with
unbelievers ;
whose portion is the lake which burns with fire and brimstone, which is the second death, (Revelation 21:8) and by these are meant, not only the Heathens, who never heard of Christ; nor the Jews only, who disbelieved the Messiah, and rejected him when he came; but all deists and atheists, who deny revelation; even all unbelievers of, and scoffers at the coming of Christ, and who put away the evil day far from them; compare with this (Job 20:29) (See Gill on Matthew 24:50), (See Gill on Matthew 24:51).