The son of Abu Said al-Khudri reported on the authority of his father that Allah's Messenger (ﷺ) said: When one of you yawns, he should try to restrain it with the help of his hand since it is the Satan that enters therein.
Related hadith on this topic
Explanation & Benefits
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary:
Benefits and Issues:
➊ In general circumstances, when one feels like yawning, one should try to restrain it.
➋ However, in the state of prayer, this emphasis is even greater.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 7493