Musnad Ahmad 1034:25

Yahya ibn Sa'id narrated to us, from Mis'ar, Wasil narrated to me, from Abu Wa'il, from Hudhayfah, that the Prophet, may Allah bless him and grant him peace, met him on one of the paths of Medina, and he (the Prophet) reached out toward him. He (Hudhayfah) said: I said, "I am in a state of major ritual impurity (junub)." He (the Prophet) said: "Indeed, the believer does not become impure."