The first two sentences you provide are *possessives*: > Ask the assistant of yours. > I hate that friend of yours. These are also possessives, and they mean the same thing: > Ask your assistant. > I hate your friend. But I think what you're asking about are *double possessives* or *double genitives*. A double possessive uses both forms of possessive at the same time. For example: > That book of David's is heavy There is a rule that states you should not use a double possessive if the object of the prepositional phrase is an *inanimate object*. So it'd be ungrammatical to say: > The laws of the church's Instead, you can say: > The laws of the church > The church's laws You might want to avoid double possessives, because a lot of them do sound awkward. There's no one rule that determines whether a double possessive sounds good or not. But nobody would say these: > I will stay at the place of my friend's. > I will stay at the place of my friend. Instead, they would say: > I will stay at my friend's place. You *could* say this, because possessive pronouns like "his" work better in double possessives: > I will stay at that place of his. There's some more information on this page: http://www.quickanddirtytips.com/education/grammar/double-possessives