Sunan Abi Dawud 76
Narrated Aisha, Ummul Mu'minin:
Dawud ibn Salih ibn Dinar at-Tammar quoted his mother as saying that her mistress sent her with some pudding (harisah) to Aisha who was offering prayer. She made a sign to me to place it down. A cat came and ate some of it, but when Aisha finished her prayer, she ate from the place where the cat had eaten.  She stated: The Messenger of Allah (ﷺ) said: It is not unclean: it is one of those who go round among you. She added: I saw the Messenger of Allah (ﷺ) performing ablution from the water left over by the cat.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ، عَنْ دَاوُدَ بْنِ صَالِحِ بْنِ دِينَارٍ التَّمَّارِ، عَنْ أُمِّهِ، أَنَّ مَوْلاَتَهَا، أَرْسَلَتْهَا بِهَرِيسَةٍ إِلَى عَائِشَةَ رضى الله عنها فَوَجَدْتُهَا تُصَلِّي فَأَشَارَتْ إِلَىَّ أَنْ ضَعِيهَا فَجَاءَتْ هِرَّةٌ فَأَكَلَتْ مِنْهَا فَلَمَّا انْصَرَفَتْ أَكَلَتْ مِنْ حَيْثُ أَكَلَتِ الْهِرَّةُ فَقَالَتْ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏
"‏ إِنَّهَا لَيْسَتْ بِنَجَسٍ إِنَّمَا هِيَ مِنَ الطَّوَّافِينَ عَلَيْكُمْ ‏"‏ ‏.‏ وَقَدْ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَتَوَضَّأُ بِفَضْلِهَا ‏.‏