Musnad Ahmad 1017:105

'Ali ibn al-Hasan—and he is Ibn Shaqiq—narrated to us, al-Husayn ibn Waqid narrated to us, Ibn Buraydah narrated to us, from his father, who said: The Messenger of Allah (ﷺ) called Bilal and said: "O Bilal, by what did you precede me into Paradise? For I entered Paradise last night and heard the rustling of your footsteps in front of me. I came upon a square palace of gold, and I said: 'To whom does this palace belong?' They said: 'To a man from the nation of Muhammad.' I said: 'I am Muhammad, to whom does this palace belong?' They said: 'To a man from the Arabs.' I said: 'I am an Arab, to whom does this palace belong?' They said: 'To a man from Quraysh.' I said: 'I am a Qurayshi, to whom does this palace belong?' They said: 'To 'Umar ibn al-Khattab.'" Bilal said: "O Messenger of Allah, I have never given the adhan without praying two rak'ahs, and no state of ritual impurity has ever befallen me without me performing wudu at that time." The Messenger of Allah (ﷺ) said: "By this."