Words cannot return void

1. Isa. 55: 11
     11 So shall my ^aword be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it.
2. Moses 4: 30
     30 For as I, the Lord God, liveth, even so my ^awords cannot return void, for as they go forth out of my mouth they must be fulfilled.