ENOfficial
Al-Bukhari reported that it was Umar, who specified Dhat 'Irq as the miqat (of those coming from Iraq).
Source: sunnah.com
Other translations
Arabic
وَفِي اَلْبُخَارِيِّ: { أَنَّ عُمَرَ هُوَ اَلَّذِي وَقَّتَ ذَاتَ عِرْقٍ } 1 .
sunnah.com