I don't like it that you distrust me so much.
Since I have given you my word for it, you could be rest assured that I would certainly do a good job out of it.
I may not be perfect, but no slipshod work of cause.

Why ask me for help in the first place when you don't even have the basic trust in me?
Yar yar I know... cause there is nobody else who is willing/able to accede to your request, or you won't even want to turn to me.
I seriously dislike that kind of feeling.