ENOfficial
It was narrated from Umm Qais bin Mihsan that she brought a small son of hers who has not started eating food to the Messenger of Allah (ﷺ). The Messenger of Allah (ﷺ) took him in his lap and he urinated on his garment, so he called for some water and sprinkled it on it, but he did not wash it.
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنْ أُمِّ قَيْسٍ بِنْتِ مِحْصَنٍ، أَنَّهَا أَتَتْ بِابْنٍ لَهَا صَغِيرٍ لَمْ يَأْكُلِ الطَّعَامَ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَأَجْلَسَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي حَجْرِهِ فَبَالَ عَلَى ثَوْبِهِ فَدَعَا بِمَاءٍ فَنَضَحَهُ وَلَمْ يَغْسِلْهُ .
sunnah.com