If a person sneezes during his prayer, should he say ‘ Al-hamdu Lillaah (Praise be to Allaah)’? If he says it, should those who hear him say, ‘ Yarhamuk Allaah (may Allaah have mercy on
you)’?
Yes, he should say that, and anyone who hears him and is not himself praying should say ‘Yarhamuk Allaah’ to him.