“Do not get any gold or silver or copper to take with you in your belts
no bag for the journey or extra shirt or sandals or a staff, for the worker is worth his keep.
What does it mean to be "worth someone's keep" ?
Keep here refers to board and lodging; subsistence; support (e.g. to work for one's keep).
Worth one's keep means one is worth the trouble of lodging and feeding him. Here the disciples are traveling, and Jesus is telling them not to provide for their own boarding; that their work will be worth board and lodging to those they come to. As Kit points out below, he is also reminding them that to be worth their keep, they must work. Conversely, they shouldn't expect free handouts if they haven't done anything.
I was just now wondering that question. Mathew 10:8 and Mathew 10:9
"... Freely you have received, freely give." "Do not take along any gold..... Sandals... staff(etc.)... ; for the worker is worth his keep."
I prayed to God and asked him to help me understand and I thought the pupose of not bringing anything(like an extra tunic) with you is probably to humble you.