The Prophet (ﷺ) sent us as an army unit of three Hundred warriors to ambush a caravan of the Quraish but they were struck with such severe hunger that they ate the Khabt (bushes or tree leaves), so that Army was called the Army of the Khabt (Jaish Al khabt), after that suddenly they got a thing to eat, which they ate for 15 days almost, what was it?