حَدَّثَنَا يَحْيَى عَنْ ابْنِ أَبِي رَوَّادٍ حَدَّثَنِي نَافِعٌ عَنِ ابْنِ عُمَرَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَأَى نُخَامَةً فِي قِبْلَةِ الْمَسْجِدِ فَحَكَّهَا وَخَلَّقَ مَكَانَهَا
مسند امام احمد بن حنبل · Hadith 4684
It was narrated from Ibn 'Umar that the Messenger of Allah (PBUH) saw some sputum in the qiblah of the mosque. He scratched it then put some khalooq (a perfume containing saffron) on that place.
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020