What is the ruling on yawning or sneezing during prayer, and should the worshipper say "Alhamdulillah" (Praise be to Allah) or "A'udhu billah" (I seek refuge in Allah) audibly or silently?

Yawning is disliked both inside and outside of prayer, and it is more intensely disliked during prayer. Whoever feels it should try to suppress it as much as possible, place their hand over their mouth, lower their voice, and not howl like a dog, for indeed, Satan laughs at him. It is recommended to seek refuge in Allah from the accursed Satan.

As for sneezing, it is from Allah. The one who sneezes should praise Allah Almighty silently during prayer, and none of the worshippers should say "Yarhamukallah" (may Allah have mercy on you) to him.