Making a Sound when Yawning in Salaah

Q: Salaah-593: As he was yawning in salaah, a person made a sound that was one or two letters long. Wilt the salaah be nullified?

Answer: If a person cannot help yawning in salaah and does so while exercising the necessary caution not to make any sounds, the salaah will still be valid. However, if he yawns carelessly and without exercising any caution, the salaah will be nullified if a sound equal to a letter or two emerged. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2