Jami` at-Tirmidhi 1598
جامع الترمذي#1598SahihNarrated Al-Bara' : "We used to say that the participants of Badr on the Day of Badr were like the number of companions of Talut, three hundred and thirteen men." [He said:] There is something on this topic from Ibn 'Abbas. [Abu 'Eisa said:] This Hadith is Hasan Sahih. Ath-Thawri and others reported it from Abu Ishaq
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
In-book reference: 21:60