John Gill Commentary Mark 13:15

"and let him that is on the housetop not go down, nor enter in, to take anything out his house:" — Mark 13:15 (ASV)

And let him that is on the house top
On the battlements of the house, either for diversion or devotion:

not go down into the house ;
in the inner way by the stairs, or ladder within doors:

neither enter therein ;
being come down from the top of the house, by stairs, or a ladder without, which was usual:

to take any thing out of his house ;
to take care of his goods, or take any thing along with him, that might be useful in his flight, and journey, and stay abroad; (See Gill on Matthew 24:17).