Musnad Ahmad 624:7

Sufyan ibn 'Uyaynah narrated to us, he said: 'Asim narrated to us, he heard Zirr ibn Hubaysh say: I came to Safwan ibn 'Assal al-Muradi, and he said: "What brought you?" I said: "Seeking knowledge." He said: "For the angels lower their wings for the seeker of knowledge, out of pleasure for what he seeks." I said: "A doubt occurred in my soul—or in my chest, as Sufyan once said—regarding wiping over the leather socks after defecation and urination. I was a man among the companions of the Messenger of Allah (peace and blessings of Allah be upon him), and I came to you to ask you if you heard anything from him regarding that." He said: "Yes, he used to command us, when we were on a journey or travelers, not to remove our leather socks for three days and their nights, except in the case of major ritual impurity (janabah), but not for defecation, urination, or sleep." I said to him: "Did you hear him mention love?" He said: "Yes. While we were with him on a journey, a Bedouin called out to him with a loud voice, saying: 'O Muhammad!' We said: 'Woe to you, lower your voice, for you have been forbidden from that.' He said: 'By Allah, I will not lower my voice.' The Messenger of Allah (peace and blessings of Allah be upon him) said: 'Here,' and he answered him in a manner similar to his question—or as Sufyan once said: 'He answered him in a manner similar to what he spoke.' He said: 'What do you say about a man who loves a people but has not yet joined them?' He said: 'He is with those whom he loves.'" He said: Then he continued to narrate to us until he said: "Indeed, in the direction of the West, there is a gate whose width is a journey of seventy or forty years, which Allah (Mighty and Majestic is He) opened for repentance on the day He created the heavens and the earth, and He will not close it until the sun rises from it."