NO!

The same for saying as you leave your child with the babysitter, "You will be okay until I get back." What this is doing is reaffirming in the child's mind that in fact things will be different while the parent(s) is gone. It only encourages the child to miss mom and dad and behave differently.

Instead, instill confidence in your child while you are gone. "You are going to have so much fun! [babysitter] is going to do art and colouring (or whatever)." Discourage worry. Instead encourage the child to make the most of it and that all will not be bad while you are gone. Make goodbyes brief and unemotional. Whatever you do avoid a long drawn out good bye. On return find out what the child did. Celebrate these happenings. 'wow, you have so much fun when I'm gone." Whatever you do it is vitally important that the child not be given the message that something might be negative until the parent gets back.