The text of Zahid, Djinn of the Lamp states that it is possible to cast it by paying an alternative cost {3}{U}, plus tapping an artifact.
However, it is necessary to specify that the artifact in question must allow its specific "to tap", otherwise the operation cannot be performed.
However, all of this at least in my opinion, which could certainly not coincide with what we all call "the truth", about this particular situation.
For example, you can cast Zahid by tapping Tormod’s Crypt, or Fountain of Youth, because these cards can be tapped to perform their specific activated abilities.
However, in my opinion it is not possible to cast Zahid by tapping, for example, Ivory Tower, or Black Vise, since these cards are always active and have no tap symbol on their text.
As a limit situation, it would be possible to cast Zahid also by tapping Howling Mine, as the latter card text clearly specifies that this card can be tapped, even if there is no "tap" symbol on the card.
Is this correct?