There is no 'phrase' per se. The spell itself is supposed to be 'worded' properly to ONLY do what you want it to do. If your NOT specific enough and leave 'loopholes' thats where the magic can have 'disastrous' results. Just saying 'harm none' somewhere will simply cancel the spell especially if it MUST do something which to the universe means 'harm' anyone. To 'us' harm means harm but what does it 'mean' to the universe ?
I generally end by stating that I leave the specifics and exact manifestations up to the Lord and Lady or whatever spirit I invoked in that particular ritual. I don't have a set phrase I always use, preferring to speak from the heart, but I essentially make it clear that while I very strongly /believe/ I have the right plan of action, the Divine knows best and I leave the ultimate decision in their enlightened and capable hands.