Answered by Shaykh Faraz Rabbani
Assalamu ‘alaykum. If one passes wind after one Salam, would this mean he would have to redo the entire Salah? Or is the Salah finished after one Salam?
Walaikum assalam wa rahmatullah,
The prayer legally ends with the first salam, but giving the second salam is necessary (wajib). Thus, if one loses wudu after one salam then one’s prayer is valid yet deficient and necessary (wajib) to repeat within the time. [Ibn Abidin, Radd al-Muhtar; Shurunbulali, Maraqi al-Falah]
And Allah alone gives success.
Faraz Rabbani