Jami` at-Tirmidhi 408
جامع الترمذي#408Da'ifAbdullah bin Amr narrated that:Allah's Messenger (S) said: "When he commits Hadath - meaning a man - and he is sitting in the end of his Salat before saying the Taslim, then his Salat is acceptable
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirDaif
Al-AlbaniDaif
Bashar Awad MaaroufDaif
Zubair Ali ZaiDaif
In-book reference: 2:261