надо and the instrumental case (knife cutting bread; a tool)

2018-04-08 04:12:14

I know about the use of dative case, or nominative case, as illustrated here: How does "следует" behave towards "должен", "надо" and "нужно" when talking about things 'one must/should/etc. do', and that is why I am confused about why this sentence;

Хлеб надо резать острым ножом.

shouldn't actually be;

Хлебу надо резать острым ножом.

Doesn't the bread need a sharp knife, like I need to drink water,

Мне надо пить воду.