Sunan Ibn Majah, Chapter: The Chapters on Ascetism (Zuhd)

"The Messenger of Allah (saw) said one day to his Companions: Who will strive hard with sincerity for Paradise? For there is nothing like Paradise. By the Lord of the Kabah, it is sparkling light, sweet basil waving in the breeze, a lofty palace, a flowing river, abundant ripe fruit, a beautiful wife and many fine garments, in a palace of eternal abode, in ease and luxury, in beautiful, strongly-built, lofty houses. They said: We will strive heard for it, O Messenger of Allah. He said: Say: In sha Allah (if Allah wills). Then he mentioned Jihad and encouraged them to engage in it."