Musannaf Ibn Abi Shaybah

Hazrat Nafi’ narrates that when Hazrat Ibn Umar (may Allah be pleased with them) would say “Yarhamukallah” to someone who sneezed, the person would reply: “Yarhamuna Allahu wa iyyakum.” And when he himself sneezed and someone said “Yarhamukallah” to him as a supplication, he would say: “Yaghfirullahu lana wa lakum wa yarhamuna wa iyyakum.”