Sahih Bukhari, Chapter: Jihaad (Fighting for the cause of Allah)

Allah's Apostle (SAW) went to the daughter of Milhan and reclined there (and slept) and then (woke up) smiling. She asked, "O Allah's Messenger! (SAW) What makes you smile?" He replied, (In a dream I saw) some people amongst my followers were sailing on the green sea in Allah's Cause, resembling kings on thrones." She said, "O Allah's Apostle (SAW)! Invoke Allah to make me one of them." Then he (slept again and woke up and) smiled. She asked him the same question and he gave the same reply. She said, "Invoke Allah to make me one of them." He replied, "You will be amongst the first group of them; you will not be amongst the last." Later on she married Ubada bin As-Samit and then she sailed on the sea with bint Qaraza, Muawiya's wife (for Jihad). On her return, she mounted her riding animal, which threw her down breaking her neck, and she died on falling down.