عَنِ النَّبِيِّ صَلَّي اللهُ عَلَيْهِ وَ آلِهٖ أَنَّهُ قَالَ مَثَلِي مَثَلُ شَجَرَةٍ أَنَا أَصْلُهَا وَ عَلِيٌّ فَرْعُهَا وَ الْحَسَنُ وَ الْحُسَيْنُ ثَمَرَتُهَا وَ الشِّيعَةُ وَرَقُهَا فَأَبَى أَنْ يَخْرُجَ مِنَ الطَّيِّبِ إِلَّا الطَّيِّبُ
The Messenger of Allah (peace be on him and his progeny) said,
“My likeness is like that of a tree; I am its root, Ali is its branch, Hasan and Husain are its fruits and the Shiites are its leaves. Thus, it is not possible that anything will come out from a pure thing except a pure thing.”
References:
1. Meezaan al-Etedaal, al-Zahabi
2. Lesaan al-Meezan, Ibn Hajar al-Makki