Musannaf Ibn Abi Shayba 17:1107

Waki’ narrated to us, from Isma’il bin Muslim, from al-Walid bin ‘Abd Allah, that the Prophet, may Allah bless him and grant him peace, passed by a leper and covered his nose. It was said to him, "O Messenger of Allah, did you not say, 'There is no contagion and no evil omens'?" He said, "Yes."