Muwatta Malik · Hadith 1065

وَحَدَّثَنِي مَالِكٌ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنِ ابْنِ وَعْلَةَ الْمِصْرِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ إِذَا دُبِغَ الإِهَابُ فَقَدْ طَهُرَ ‏"‏ ‏.‏

Malik related to me from Zayd ibn Aslam from Ibn Wala al-Misri from Abdullah ibn Abbas that the Messenger of Allah, may Allah bless him and grant him peace, said, "A skin when it is tanned is pure

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).