Translation of the verse 20 from Surah Qaf : Number of verses 45 - - page 519 - Part 26.
And the Trumpet will be blown, that will be the Day whereof warning (had been given) (i.e. the Day of Resurrection).
And the Horn will be blown. That is the Day of [carrying out] the threat.
(50:20) And then the Trumpet was blown. *24 This is the day of the promised chastisement.
*24) This implies that blowing of the Trumpet at which alI dead men will rise back to life in their own physical bodies. For explanation, see E.N. 47 of AIAn'am, E.N. 57 of Ibrahim, E.N. 78 of Ta. Ha, E.N.1 of AI-Hajj, E.N.'s 46,47 of Ya Sin, and E.N. 79 of Az-Zumar.
Source : Qaf Verse 20: And the Horn will be blown. That is the Day of [carrying out] the threat.