Jāmiʿ at-Tirmidhī 3710

The full narration

Narrated Abu Musa Al-Ash'ari:"I went with the Prophet (ﷺ) and he entered a garden of the Ansar, and he relieved himself. He said to me: 'O Abu Musa! Watch the gate for me, and do not let anyone enter except with permission.' Then a man came and knocked at the gate, so I said: 'Who is it?' He said: 'Abu Bakr.' So I said: 'O Messenger of Allah (ﷺ)! It is Abu Bakr asking permission?' He said: 'Give him permission and give him the glad tidings of Paradise.' So he entered, and I gave him the glad tidings of Paradise. Another man came and knocked at the gate. I said: 'Who is it?' He said: "'Umar.' So I said: 'O Messenger of Allah (ﷺ)! It is 'Umar asking permission?' He said: 'Open it for him, and give him the glad tidings of Paradise.' I opened [the gate], he entered, and I gave him the glad tidings of Paradise. Then another man knocked at the gate. I said: 'Who is it?' So he said: ''Uthman.' I said: 'O Messenger of Allah! It is 'Uthman asking permission.' He said: 'Open it for him, and give him the glad tidings of Paradise due to a calamity that will befall him