If an Izar is not available, one can wear trousers
باب إِذَا لَمْ يَجِدِ الإِزَارَ فَلْيَلْبَسِ السَّرَاوِيلَ
Sahih al-Bukhari, Book of Penalty of Hunting while on Pilgrimage(view book)
Sahih al-Bukhari 1843
Narrated Ibn Abbas:
The Prophet delivered a sermon at 'Arafat and said, "Whoever does not get an Izar can wear trousers, and whoever cannot get a pair of shoes can wear Khuffs."
حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا عَمْرُو بْنُ دِينَارٍ، عَنْ جَابِرِ بْنِ زَيْدٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ خَطَبَنَا النَّبِيُّ ﷺ بِعَرَفَاتٍ فَقَالَ " مَنْ لَمْ يَجِدِ الإِزَارَ فَلْيَلْبَسِ السَّرَاوِيلَ، وَمَنْ لَمْ يَجِدِ النَّعْلَيْنِ فَلْيَلْبَسِ الْخُفَّيْنِ ".
Classification
Sahih (Authentic)