What did the Prophet Muhammad (saw) do when Abu Bakr and 'Umar (peace be upon him) asked for permission to enter the place called Bir Aris?
 Narrated Abu Musa Al-Ash`ari:                     I performed ablution in my house and then went out and said, "Today I shall stick to Allah's Apostle and stay with him all this day of mine (in his service)." I went to the Mosque and asked about the Prophet . They said, "He had gone in this direction." So I followed his way, asking about him till he entered a place called Bir Aris. I sat at its gate that was made of date-palm leaves till the Prophet finished answering the call of nature and performed ablution. Then I went up to him to see him sitting at the well of Aris at the middle of its edge with his legs uncovered, hanging in the well. I greeted him and went back and sat at the gate. I said, "Today I will be the gatekeeper of the Prophet." Abu Bakr came and pushed the gate. I asked, "Who is it?" He said, "Abu Bakr." I told him to wait, went in and said, "O Allah's Apostle! Abu Bakr asks for permission to enter." He said, "Admit him and give him the glad tidings that he will be in Paradise." So I went out and said to Abu Bakr, "Come in, and Allah's Apostle gives you the glad tidings that you will be in Paradise" Abu Bakr entered and sat on the right side of Allah's Apostle on the built edge of the well and hung his legs n the well as the Prophet did and uncovered his legs. I then returned and sat (at the gate). I had left my brother performing ablution and he intended to follow me. So I said (to myself). "If Allah wants good for so-and-so (i.e. my brother) He will bring him here." Suddenly somebody moved the door. I asked, "Who is it?" He said, "`Umar bin Al-Khattab." I asked him to wait, went to Allah's Apostle, greeted him and said, `Umar bin Al-Khattab asks the permission to enter." He said, "Admit him, and give him the glad tidings that he will be in Paradise." I went to "`Umar and said "Come in, and Allah's Apostle, gives you the glad tidings that you will be in Paradise." So he entered and sat beside Allah's Apostle on the built edge of the well on the left side and hung his legs in the well. I returned and sat (at the gate) and said, (to myself), "If Allah wants good for so-and-so, He will bring him here." Somebody came and moved the door. I asked "Who is it?" He replied, "Uthman bin `Affan." I asked him to wait and went to the Prophet and informed him. He said, "Admit him, and give him the glad tidings of entering Paradise, I asked him to wait and went to the Prophet and informed him. He said, "Adult him, and give him the glad tidings of entering Paradise after a calamity that will befall him." So I went up to him and said to him, "Come in; Allah's Apostle gives you the glad tidings of entering Paradise after a calamity that will befall you. "Uthman then came in and found that the built edge of the well was occupied, so he sat opposite to the Prophet on the other side. Sa`id bin Al-Musaiyab said, "I interpret this (narration) in terms of their graves."