Jami` at-Tirmidhi 730

جامع الترمذي#730Da'if

Hafsah narrated that:the Prophet said: "Whoever did not decide to fast before Fajr then there is no fast for him

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: 8:49