"We do not trust you!"
Translation:Nie ufamy tobie!
„tobie” is a dative and locative of „ty”, though the dative is the stressed form – you probably already seen the mute form „ci”.
The verb „ufać” is intransitive, so you can't have a direct object with it and „ci”/„tobie”/„wam” can be thought of as an indirect object, which requires dative in Polish.
To simplify, a direct object is the thing that the verb acts upon, whereas an indirect object is the recipient/beneficiary of the verb:
- "She gives Peter the book" = "She gives [indirect object] [direct object]"
Polish (unlike English) is not a positional language, so the order of objects doesn't matter – we know which is which thanks to the case system, in positive statements a direct object is almost always marked by an accusative case and an indirect object is always (as far as I know) marked by a dative case. In negations, if the direct object was marked by an accusative case, it changes to a genitive case.
BTW, just for the sake of completeness and to maybe help understanding the case system, you can actually stretch English to mark object by case, if you use pronouns:
- "I give him a book" vs.
- "Me gives he a book" – this might not be very natural sentence, but you still know who gives what to whom, thanks to the case system. ;)