Sunan Ibn Majah, Hadith 658 ⓘ
It was narrated that Abu Hurairah said: "I saw the Prophet carrying Hasan bin 'Ali on his shoulder, and his saliva was dripping down on him."
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، عَنْ حَمَّادِ بْنِ سَلَمَةَ، عَنْ مُحَمَّدِ بْنِ زِيَادٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ رَأَيْتُ النَّبِيَّ ـ صلى الله عليه وسلم ـ حَامِلَ الْحُسَيْنِ بْنِ عَلِيٍّ عَلَى عَاتِقِهِ وَلُعَابُهُ يَسِيلُ عَلَيْهِ .
also referenced under: Book 1, Hadith 703 (In-Book) & Volume 1, Book 1, Hadith 658 (DarusSalam)