Does the reward of one who prays Fajr in congregation then sits in his prayer place remembering Allah become nullified if he passes wind?

Impurities (hadath) do not invalidate the action itself, but only invalidate ritual purity (tahara). So, if someone experiences an impurity while in their prayer area, waiting for the sunrise prayer, the reward for their action is not lost. However, scholars have differed on whether the reward for the sunrise prayer is forfeited by leaving for ablution (wudu) or other reasons, because the reward is conditional upon certain requirements, including remaining in the prayer area until the sun rises. Most scholars are of the opinion that the promise [of reward] is specific to those who sit in their prayer area and do not leave it. Whereas some scholars have permitted standing up for circumambulation (tawaf), seeking knowledge, attending a sermon in the mosque, or even returning home and continuing remembrance (dhikr). For someone whose departure was due to an unavoidable excuse, such as performing ablution, we hope they will still attain the reward based on their intention.