As the story goes...Muhammad was heard to say that after his business in Jerusalem was finished a ladder finer than any he had ever seen was brought to him. Gabriel climbed it with him to reach one of the gates of heaven, the Gate of the Watchers. He was introduced to Isma'il, an angel in charge of the gate under whose command were 12,000 angels each of them commanding 12,000 angels. Learning Muhammad had been sent for, Isma'il wished him well. (Cf. 184f, A.Guillaume, The LIfe of Muhammad.)