عَبْدِ بْنِ حُمَيْدٍ الْكَشِّيِّ
1  
`Abd ibn Humayd al-Kashshi
Abū al-Ḥamrāʾ (may Allah be pleased with him) reported:
I accompanied the Prophet ﷺ for nine months, and whenever he entered the morning he would come to the door of ʿAlī and Fāṭimah (may Allah be pleased with them) and say: "May Allah have mercy on you — Allah only intends to remove impurity from you, O people of the House, and to purify you with a thorough purification." Reference: Thulāthiyyāt ʿAbd ibn Ḥumayd al-Kashshī 3
وَبِهِ قَالَ: حَدَّثَنِي الضَّحَّاكُ بْنُ مَخْلَدٍ، قَالَ: حَدَّثَنِي أَبُو دَاوُدَ السَّبِيعِيُّ، قَالَ: حَدَّثَنِي أَبُو الْحَمْرَاءِ، قَالَ: صَحِبْتُ النَّبِيَّ ﷺ تِسْعَةَ أَشْهُرٍ، وَكَانَ إِذَا أَصْبَحَ أَتَى بَابَ عَلِيٍّ وَفَاطِمَةَ وَهُوَ يَقُولُ: «يَرْحَمُكُمُ اللَّهُ، إِنَّمَا يُرِيدُ اللَّهُ لِيُذْهِبَ عَنْكُمُ الرِّجْسَ أَهْلَ الْبَيْتِ، وَيُطَهِّرَكُمْ تَطْهِيرًا».
Grade: Ḍaʿīf jiddan from Abū al-Ḥamrāʾ's narration specifically ("his ḥadīth is not sound," per al-Bukhārī), but ṣaḥīḥ from the corroborating narration of Anas ibn Mālik (may Allah be pleased with him)
Arabic/English book reference : Book 1, Hadith 3