Ask for one thing / Ask one thing (Which one is correct?)
I would like to know which form I should use "to ask FOR one thing" or "to ask for one thing" when I want to convey the meaning of requesting something. My confusion is because I have seen people use those two expressions. Something makes me think that the form using "FOR" should be the only correct, but I am not sure.
Examples:
1.a. The only thing I ask FOR is...
1.b. The only thing I ask is...
2.a. Laura, I would like to ask you FOR one thing, be my girl.
2.b. Laura, I would like to ask you one thing, be my girl.