Sahih Bukhari Volume 9, Book 87, Hadith Number 142.

Narrated By ‘Abdullah bin Salam : (In a dream) I saw myself in a garden, and there was a pillar in the middle of the garden, and there was a handhold at the top of the pillar. I was asked to climb it. I said, “I cannot.” Then a servant came and lifted up my clothes and I climbed (the pillar), and then got hold of the handhold, and I woke up while still holding it. I narrated that to the Prophet who said, “The garden symbolizes the garden of Islam, and the handhold is the firm Islamic handhold which indicates that you will be adhering firmly to Islam until you die.”