Language:
كتاب الأذان
10  
Call to Prayers (Adhaan)
(136)
Chapter: To tie the clothes and wrap them properly [in Salat (prayer)]; and whoever gathered his clothes for fear that his private parts may become exposed.
(136)
باب عَقْدِ الثِّيَابِ وَشَدِّهَا
Sahih al-Bukhari 814

Narrated Sahl bin Sa`d:

The people used to pray with the Prophet (ﷺ) tying their Izars around their necks because of their small sizes and the women were directed that they should not raise their heads from the prostrations till the men had sat straight.

حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، قَالَ أَخْبَرَنَا سُفْيَانُ، عَنْ أَبِي حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ، قَالَ كَانَ النَّاسُ يُصَلُّونَ مَعَ النَّبِيِّ صلى الله عليه وسلم وَهُمْ عَاقِدُو أُزْرِهِمْ مِنَ الصِّغَرِ عَلَى رِقَابِهِمْ فَقِيلَ لِلنِّسَاءِ لاَ تَرْفَعْنَ رُءُوسَكُنَّ حَتَّى يَسْتَوِيَ الرِّجَالُ جُلُوسًا‏.‏
Reference : Sahih al-Bukhari 814
In-book reference : Book 10, Hadith 209
USC-MSA web (English) reference : Vol. 1, Book 12, Hadith 778
  (deprecated numbering scheme)