David. R. Goodworth explores saying 2.2/Th21 from his book 'The Gospel of Thomas: Evolution'.

Mary said to Jesus, “Who are your disciples like?” He said, “They are like little children living in a field which is not theirs. When the Lords of the field come, they say, ‘Give us our field back.’ They (the children) remove their garments in front of them to give those back, and they give the field back to them.

Therefore, I say this, If the owner of the house knows that the thief is coming, they will keep watch before he comes, and will not let him dig into their house, to carry off their belongings. You must also be on guard and be aware of the world. Prepare yourself with great strength, or the robbers will find a way to reach you, for the problems you expect will surely come.  ...