Just leave it there. I'll take care of it

Have you ever had someone want to help you, but because you know it needs to be done a certain way, you say, "Just leave it there.  I'll take care of it"? I have.  It's not that I'm a perfectionist or anything, but I know if someone else tries to "organize" my lab at school, I will have to go redo it.  Things have to be in the right place in order for labs to run smoothly.  Even at home, there are things that I need to do myself in order for things to work the way I want them to.
I was thinking about this recently and wondered how many times God says, "Just leave it there.  I'll take care of it."  The problem is...we think we know better and don't trust Him to take care of the issue.  The act of physically placing something on the altar and giving it to God is very powerful.  It means trusting Him.  When there comes a time that you need it back, all you had to do is tell God that you don't think He is capable enough to handle it and take it back off of the altar.  He won't force you to leave it there.
When I was thinking about this, it was in the context of someone else.   Then today came and I am confronted with a situation that I have to take to the altar and leave it there for God to take care of.  As much as I think I know, He knows best and can handle the situation far better than I can.
I'm wondering...What is it that you need to take to the altar and leave there?  Is God big enough to handle it?