Which event was experienced by Abu Musa while in the company of the Prophet Muhammad (saw) in one of the gardens of Medina?
 Narrated Abu Musa:                     That he was in the company of the Prophet in one of the gardens of Medina and in the hand of the Prophet there was a stick, and he was striking (slowly) the water and the mud with it. A man came (at the gate of the garden) and asked permission to enter. The Prophet said, "Open the gate for him and give him the glad tidings of entering Paradise. "I went, and behold! It was Abu Bakr. So I opened the gate for him and informed him of the glad tidings of entering Paradise. Then another man came and asked permission to enter. The Prophet said, "Open the gate for him and give him the glad tidings of entering Paradise." Behold! It was `Umar. So I opened the gate for him and gave him the glad tidings of entering Paradise. Then another man came and asked permission to enter. The Prophet was sitting in a leaning posture, so he sat up and said, "Open the gate for him and give him the glad tidings of entering Paradise with a calamity which will befall him or which will take place." I went, and behold ! It was `Uthman. So I opened the gate for him and gave him the glad tidings of entering Paradise and also informed him of what the Prophet had said (about a calamity). `Uthman said, "Allah Alone Whose Help I seek (against that calamity).