Narrated Nafi': That Ibn 'Umar said: "When the Messenger of Allah (ﷺ) would wear an 'Imamah would hang between his shoulders." Nafi' said: "Ibn 'Umar would hang his 'Imamah between his shoulders." 'Ubaidullah said: "And I saw Al-Qasim and Salim doing that." This Hadith is Hasan Gharib. And there is something on this topic from 'Ali. And this Hadith of 'Ali about this is not correct due to its chain.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا هَارُونُ بْنُ إِسْحَاقَ الْهَمْدَانِيُّ، حَدَّثَنَا يَحْيَى بْنُ مُحَمَّدٍ الْمَدَنِيُّ، عَنْ عَبْدِ الْعَزِيزِ بْنِ مُحَمَّدٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا اعْتَمَّ سَدَلَ عِمَامَتَهُ بَيْنَ كَتِفَيْهِ . قَالَ نَافِعٌ وَكَانَ ابْنُ عُمَرَ يَسْدِلُ عِمَامَتَهُ بَيْنَ كَتِفَيْهِ . قَالَ عُبَيْدُ اللَّهِ وَرَأَيْتُ الْقَاسِمَ وَسَالِمًا يَفْعَلاَنِ ذَلِكَ . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ . وَفِي الْبَابِ عَنْ عَلِيٍّ وَلاَ يَصِحُّ حَدِيثُ عَلِيٍّ فِي هَذَا مِنْ قِبَلِ إِسْنَادِهِ .
sunnah.com