Hawzah News Agency – Shuayb b. Abd al-Rahman al-Khuzai said:

وُجِدَ عَلى ظَهرِالحُسَينِ بنِ عَليٍّ يَومَ الطَّفِّ أثَرٌ، فَسَألوا زَينَ العابِدينَ عَن ذلك فَقالَ: هذا مِمّا كانَ يَنقُلُ الجَرابَ عَلى ظَهرِهِ إلى مَنازِلَ الأرامِلِ وَاليَتامى وَالمَساكينَ.

'A mark was seen on Husayn's back on the day of Taff [Ashura'], so they asked Zayn al-Abidin [about it], and he replied, 'This is the mark left by the sacks [of food] he carried on his back to the houses of widows, orphans and the destitute.'

Source: Manaqib Ibn Shahr Ashub, v. 4, p. 66