People typically left a cloak in their homes when they went to work in the fields, or they put it safely to the side somewhere nearby. Jesus is saying that believers should make haste to escape from Judea when they see the abomination that causes desolation standing in the holy place. There will be no time to take a small detour and go to collect your cloak.1
18 and let the one who is in the field not turn back to take his cloak.