It is narrated from Nafi‘ that when Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) sneezed and someone said «يَرْحَمُكَ اللّٰهُ» (may Allah have mercy on you), he would say «يَرْحَمُنَا اللّٰهُ وَإِيَّاكُمْ، وَيَغْفِرُ لَنَا وَلَكُمْ» , (meaning: May Allah have mercy on us and on you, and forgive us and forgive you).