"A Bedouin came to the Prophet (S.a.w) and said: 'What is the Sur?' He said: 'A horn that will be blown into'" This Hadith is Hasan Sahih. It has been reported by more than one narrator from Sulaimãn At-Taimi, and we do not know of it except as his narration.
Jami` at-Tirmidhi Book 37, Hadith 16
← Previous Hadith "The Messenger of Allah (s.a.w) recited: That Day it will declare its information. And said: 'Do you know what its information is?' they said: 'Allah and His Messenger know best.' He said: 'Indeed its information is that it will testify against every servant, male and female, It will say that he did such and such, on such and such a day.' He said: 'With this it shall be ordered.'" This Hadith is Hasan Gharib.

Jami` at-Tirmidhi Book 37, Hadith 15 Next Hadith → "The Messenger of Allah (s.a.w) said: 'How can I be comfortable when the one with the horn is holding it to his lip, his ears listening for when he will be ordered to blow, so he can blow.' It was as if that was very hard upon the Companions of the Prophet (s.a.w), so he said to them: 'Say: "Allah is sufficent for us and what a good protector He is, and upon Allah we rely." This Hadith is Hasan. This Hadith has been reported through other routes from 'Atiyyah, from Abu Sa'eed from the Prophet SAW, similarly.

Jami` at-Tirmidhi Book 37, Hadith 17