would you as a parent tell your young toddler that "mommy and daddy will always come back" ???

if you were leaving your toddler with a babysitter for a few hours or even their grandparents or aunts/uncles were watching them for you, is this something you would tell them before you leave??

i have no kids so can't really be an 'expert' on something like this (but do have four nieces and nephews). but this seems like a not-so-good thing to instill in a young child, especially these days when anything can happen and at any time! as in, car accidents, shootings, muggings/car-jackings, bombings, and other accidents or tragedies ..... or is this just something you temporarily tell a young child who hasn't had an 'easy' life up to that point, as in maybe a situational-thing or something that varies from family to family??