Narrated Al-Harith ibn Amr as-Sahmi: I came to the Messenger of Allah (ﷺ) when he was at Mina, or at Arafat. He was surrounded by the people. When the bedouins came and saw his face, they would say: This is a blessed face. He said: He (the Prophet) appointed Dhat Irq as the place of putting on ihram for the people of Iraq.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو مَعْمَرٍ عَبْدُ اللَّهِ بْنُ عَمْرِو بْنِ أَبِي الْحَجَّاجِ، حَدَّثَنَا عَبْدُ الْوَارِثِ، حَدَّثَنَا عُتْبَةُ بْنُ عَبْدِ الْمَلِكِ السَّهْمِيُّ، حَدَّثَنِي زُرَارَةُ بْنُ كُرَيْمٍ، أَنَّ الْحَارِثَ بْنَ عَمْرٍو السَّهْمِيَّ، حَدَّثَهُ قَالَ أَتَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم وَهُوَ بِمِنًى أَوْ بِعَرَفَاتٍ وَقَدْ أَطَافَ بِهِ النَّاسُ قَالَ فَتَجِيءُ الأَعْرَابُ فَإِذَا رَأَوْا وَجْهَهُ قَالُوا هَذَا وَجْهٌ مُبَارَكٌ . قَالَ وَوَقَّتَ ذَاتَ عِرْقٍ لأَهْلِ الْعِرَاقِ .
sunnah.com