Merits of the Helpers in Madinah (Ansaar)
حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا إِسْحَاقُ بْنُ سَعِيدٍ السَّعِيدِيُّ، عَنْ أَبِيهِ، عَنْ أُمِّ خَالِدٍ بِنْتِ خَالِدٍ، قَالَتْ قَدِمْتُ مِنْ أَرْضِ الْحَبَشَةِ وَأَنَا جُوَيْرِيَةٌ، فَكَسَانِي رَسُولُ اللَّهِ صلى الله عليه وسلم خَمِيصَةً لَهَا أَعْلاَمٌ، فَجَعَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَمْسَحُ الأَعْلاَمَ بِيَدِهِ وَيَقُولُ " سَنَاهْ، سَنَاهْ ". قَالَ الْحُمَيْدِيُّ يَعْنِي حَسَنٌ حَسَنٌ.Narrated Um Khalid bint Khalid:When I came from Ethiopia (to Medina), I was a young girl. Allah's Messenger (ﷺ) made me wear a sheet having marks on it. Allah's Messenger (ﷺ) was rubbing those marks with his hands saying, "Sanah! Sanah!" (i.e. good, good)
From Sahih al-Bukhari, whose reports the scholars accept as authentic.