Musnad Ahmad 39:3

Yazid ibn Harun narrated to us, Muhammad ibn Amr informed us, from Abu Salamah, who said: Nafi ibn al-Harith said: I went out with the Messenger of Allah, may Allah bless him and grant him peace, until he entered a garden. He said to me: "Guard the door for me." He came and sat on the edge of the well and dangled his feet into the well. Then someone knocked on the door. I said: "Who is this?" He said: "Abu Bakr." I said: "O Messenger of Allah, this is Abu Bakr." He said: "Give him permission and give him glad tidings of Paradise." I gave him permission and gave him glad tidings of Paradise. He entered and sat with the Messenger of Allah, may Allah bless him and grant him peace, on the edge of the well and dangled his feet into the well. Then someone knocked on the door. I said: "Who is this?" He said: "Umar." I said: "O Messenger of Allah, this is Umar." He said: "Give him permission and give him glad tidings of Paradise." I gave him permission and gave him glad tidings of Paradise. He entered and sat with the Messenger of Allah, may Allah bless him and grant him peace, on the edge of the well and dangled his feet into the well. Then someone knocked on the door. I said: "Who is this?" He said: "Uthman." I said: "O Messenger of Allah, this is Uthman." He said: "Give him permission and give him glad tidings of Paradise, along with a trial that will befall him." I gave him permission and gave him glad tidings of Paradise. He entered and sat with the Messenger of Allah, may Allah bless him and grant him peace, on the edge of the well and dangled his feet into the well.