Musnad Ahmad 534:21

Abu al-Mughirah narrated to us, he said: Safwan narrated to us, he said: Yazid ibn Khumayr al-Rahbi narrated to me, from Abdullah ibn Busr al-Mazini, from the Messenger of Allah (may Allah bless him and grant him peace) that he said: "There is no one from my nation except that I will recognize him on the Day of Resurrection." They said: "And how will you recognize them, O Messenger of Allah, amidst the multitude of creatures?" He said: "Do you see, if you entered a pile of grain containing black horses, and among them was a horse with a white blaze on its forehead and white markings on its legs, would you not recognize it among them?" He said: "Yes." He said: "For my nation on that day will have white blazes from prostration, and white markings from ablution." *** 17694 - Al-Hakam ibn Musa narrated to us, he said: Abdullah [said], and I heard it from al-Hakam, he said: Baqiyyah narrated to us, he said: And Muhammad ibn Abd al-Rahman al-Yahsubi narrated to me, he said: I heard Abdullah ibn Busr, the companion of the Prophet (may Allah bless him and grant him peace), saying: "When the Messenger of Allah (may Allah bless him and grant him peace) would come to a door to ask for permission, he would not face it directly." He said: "He would walk along the side of the wall until he asked for permission, so he would be given permission, or he would depart."