Bulugh al-Maram

Al-Bukhari reported that it was Umar, who specified Dhat 'Irq as the miqat (of those coming from Iraq).

وَفِي اَلْبُخَارِيِّ: { أَنَّ عُمَرَ هُوَ اَلَّذِي وَقَّتَ ذَاتَ عِرْقٍ } 1‏ .‏