Al-Kāfi - Volume 3 > Urine Comes in Contact with One’s Clothes or Body
Hadith #5

5ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ عَبْدِ الله بْنِ الْمُغِيرَةِ أَنَّهُ قَالَ فِي كِتَابِ سَمَاعَةَ رَفَعَهُ إِلَى أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) إِنْ أَصَابَ الثَّوْبَ شَيْ‏ءٌ مِنْ بَوْلِ السِّنَّوْرِ فَلاَ تَصِحُّ الصَّلاَةُ فِيهِ حَتَّى تَغْسِلَهُ.

5. Ali ibn Ibrahim has narrated from his father from ‘Abd Allah ibn al-Mughirah who has said that it is in the book of Sama‘ah who in a marfu‘ manner has narrated the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘If clothes come in contact with the urine of cats, performing Salah (prayer) with such clothes is not valid until they are washed.’”