How long with Prophet Muhammad (saw) did Ibn `Abbas and his companions stay on their journey, during which they offered Qasr (shortened) prayers?
 Narrated `Ikrima:                     Ibn `Abbas said, "We stayed for 19 days with Prophet on a journey during which we used to offer shortened prayers." Ibn `Abbas added, "We offer the Qasr prayer (i.e. shortened prayer) If we stay up to 19 days as travelers, But if we stay longer, we offer complete prayers.