Musannaf Ibn Abi Shayba 3:1040

Waki’ narrated to us, from Sufyan, from Abu Ishaq, from Sa’d ibn Abi Hudan, from Alqama, that when he would enter the mosque, he would say: "Peace be upon you, O Prophet, and the mercy of Allah and His blessings. May Allah and His angels send blessings upon Muhammad."