It has been confirmed in a Hadith that the Messenger of Allah was asked about the Sur and he replied,

“It is a horn that will be blown into.”

It has been related in a Hadith about the Sur, on the authority of Abu Hurayrah that it is a huge horn that has circumference as large as the heavens and the earth. The angel Israfil will blow into it. Another Hadith has been related which states that the Prophet said,

“How can I be comfortable when the one with the horn is holding it in his lips and his forehead is leaning forward, waiting to be given permission (to blow it).”

The people said, “O Messenger of Allah, what should we say?” He said,

“Say: Allah is sufficient for us and what a good protector He is. Upon Allah we place our trust.”

Concerning His statement,

It has been said that this means having blue eyes due to the severity of their horrifying situation.

Ibn ‘Abbas said, “This means whispering among themselves.” This means that some of them will be saying to others,

meaning in the abode of the worldly life, you only tarried there for a little while. The time was equivalent to ten days or so. Allah, the Exalted, then says,

This means in their condition of conversing amongst themselves.

the one with perfect intelligence amongst them,

This is because on the Day of Judgement they will sense the shortness of the worldly life within themselves. For the worldly life, with its repetitious time periods and successive nights, days and hours, is as if it is just one day. For this reason, on the Day of Resurrection the disbelievers will think the worldly life was very short. By this they mean to prevent the establishment of the evidence against them due to the shortness of time that they had. Allah says about this,

{And on the Day that the Hour will be established, the criminals will swear that they stayed not but an hour} until His statement. {but you knew not.”} [30:55-56]

Allah also says,

{Did We not give you lives long enough, so that whosoever would receive admonition could receive it? And the wamer came to you.} [35:37]

Allah, the Exalted, also says,

{(Allah will say): What number of years did you stay on earth? They will say: "We stayed a day or part of a day. Ask of those who keep account." He (Allah) will say: "You stayed not but a little, if you had only known!"} [23:112-114]

This means that you only remained in it (the earth) a little while. If you only knew, you would have preferred the eternal life over the temporal life. Yet, you conducted yourselves in an evil manner. You gave the present, temporary life precedence over the eternal and everlasting life.