Sahih Muslim 287a
Sahih Muslim · Book 2: The Book of Purification · The ruling on the urine of a nursing infant and how to wash it
حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحِ بْنِ الْمُهَاجِرِ ، أَخْبَرَنَا اللَّيْثُ ، عَنِ ابْنِ شِهَابٍ ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ ، عَنْ أُمِّ قَيْسٍ بِنْتِ مِحْصَنٍ ، أَنَّهَا أَتَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم بِابْنٍ لَهَا لَمْ يَأْكُلِ الطَّعَامَ فَوَضَعَتْهُ فِي حِجْرِهِ فَبَالَ - قَالَ - فَلَمْ يَزِدْ عَلَى أَنْ نَضَحَ بِالْمَاءِ .
Umm Qais daughter of Mihsan reported that she came to the Messenger of Allah (ﷺ) with her child. who was not yet weaned, and she placed him in his lap; and he urinated in his (Holy Prophet's) lap. He (the Holy Prophet) did nothing more than spraying water over it.