Musannaf Ibn Abi Shayba 21:649

Waki’ narrated to us, from Sufyan, from Abu Ishaq, from Sa’id ibn Dhi Haddan, from Alqama, that he: When he entered 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."