Abu Dharr reported: The Prophet, peace and blessings be upon him, came out during the winter while the leaves fell from the trees. He took hold of two branches and shook them until the leaves fell. The Prophet said, “O Abu Dharr!” I said, “Here I am, O Messenger of Allah.” The Prophet said, “Verily, when a Muslim servant performs prayer seeking the countenance of Allah, his sins will fall away just as these leaves fall from this tree.”
Source: Musnad Aḥmad 21556
Grade: Hasan li ghayrihi (fair due to external evidence) according to Al-Arna’ut
عَنْ أَبِي ذَرٍّ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ خَرَجَ زَمَنَ الشِّتَاءِ وَالْوَرَقُ يَتَهَافَتُ فَأَخَذَ بِغُصْنَيْنِ مِنْ شَجَرَةٍ قَالَ فَجَعَلَ ذَلِكَ الْوَرَقُ يَتَهَافَتُ قَالَ فَقَالَ يَا أَبَا ذَرٍّ قُلْتُ لَبَّيْكَ يَا رَسُولَ اللَّهِ قَالَ إِنَّ الْعَبْدَ الْمُسْلِمَ لَيُصَلِّ الصَّلَاةَ يُرِيدُ بِهَا وَجْهَ اللَّهِ فَتَهَافَتُ عَنْهُ ذُنُوبُهُ كَمَا يَتَهَافَتُ هَذَا الْوَرَقُ عَنْ هَذِهِ الشَّجَرَةِ
21556 مسند أحمد بن حنبل
22/58 المحدث شعيب الأرناؤوط خلاصة حكم المحدث حسن لغيره في تخريج المسند لشعيب