Musannaf Ibn Abi Shayba 16:592

Abu Bakr narrated to us, he said: Abu Khalid al-Ahmar narrated to us, from Abu Ghifar, from Abu Tamima al-Hujaymi, from Abu Jurayy al-Hujaymi, who said: I came to the Messenger of Allah, may Allah bless him and grant him peace, and I said: "‘Alayka as-salam (upon you be peace), O Messenger of Allah." He said: "Do not say ‘Alayka as-salam, for ‘Alayka as-salam is the greeting of the dead. And beware of letting the lower garment hang low (isbal al-izar), for it is from arrogance."