Mu'adh b. Jabal said that the Prophet used to like to pray in al-hitan*. One of its transmitters says that it means gardens.
* I have given the Arabic word because it is explained in the text. Why it should need to be explained is not clear.
Tirmidhi transmitted it and said, “This is a gharib tradition which we know only among the traditions of al-Hasan b. Abu Ja'far whom Yahya b. Sa'id and others have declared to be weak.”