Jami` at-Tirmidhi 417
جامع الترمذي#417Da'ifIbn Umar narrated:"I watched the Prophet (S) for a month. In the two Rak'ah before Fajr he would recite: Say: "O you disbelievers!" and Say: "Allah is One
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
Zubair Ali ZaiDaif
In-book reference: 2:270