Musannaf Ibn Abi Shayba 3:1039

Abu ‘Amir al-‘Aqadi narrated to us, from ‘Ali ibn al-Mubarak, from Yahya ibn Abi Kathir, from Muhammad ibn ‘Abd al-Rahman, that ‘Abd Allah ibn Salam, when he would enter the mosque, would greet the Prophet (may Allah bless him and grant him peace) and say: "O Allah, open for me the doors of Your mercy." And when he would leave, he would greet the Prophet (may Allah bless him and grant him peace) and seek refuge from Satan.