مختصر صحيح بخاري
Mukhtasar Sahih Bukhari
Book of Beginning of Creation
What is narrated about Paradise and that it is already created.
Narrated by Sayyiduna Anas (may Allah be pleased with him) from the Noble Prophet (peace and blessings be upon him) that he (peace be upon him) said: "In Paradise, there is a tree such that if a rider were to travel in its shade for a hundred years, he would still not be able to cross it (this tree is Tuba)."