Jami` at-Tirmidhi 247
جامع الترمذي#247SahihUbadah bin As-Samil narrated that :the Prophet said: "There is no Salat for the one who does not recite Fatihatil-Kitab
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 2:99