Would saying Astaghfirullah after yawning break the Salah.
In the name of Allah, the most Beneficent, the most Merciful.
Saaiduna Abu Said al Khudri narrates that the Prophet of Allah said: “If any of you yawns, let him cover his mouth lest the Shaitan enter.” (Sunan Abu Dawuud)
We can derive from the aforementioned hadith that yawning is considered as one of the disliked actions of salah. (Raddul Muhtar p.412 v.2)
One should try to suppress the yawning and hold it by clinching the upper and lower jaws and closing the lips tightly. One can also use the back of his right hand to cover his mouth in Qiyam (standing position) as the right hand it is on top of the left hand in the Qiyam position thus, requires less movement. In Ruku, Sujud, Tashahhud etc… one should use the back of the left hand. (Raddul Muhtar p.413 v.2)
Regarding your question, remember any Zikr of Allah (in Arabic) does not invalidate the salah, hence, if you did say Astaghfirullah after yawning it will not break your salah. (Ilmul Fiqh p.101 v.2)
However, it should be borne in mind that it is not a sunnah to say Astaghfirullah after yawning unlike after sneezing where it is a sunnah to say Alhamdulilah.
Saaiduna Abu Hurairah narrates that the Prophet of Allah said: “If any one of you sneezes, let him say ‘Al-hamdu Lillaah,’ and let his brother or his companion say, ‘Yarhamuk Allah.’ And if he says to him, ‘Yarhamuk Allah,’ let him say, ‘Yahdeekum Allahu wa yuslihu baalakum.’” (Sahih Bukhari)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham