What is the ruling on buying ivory?

Scholars differed on the ruling regarding the sale of ivory, depending on their differing views on its purity (tahara) and impurity (najasa). Those who deemed it impure prohibited its sale, while those who considered it pure permitted it. The Shafi'is and Hanbalis prohibited its sale. The Malikis disliked the use of ivory from an elephant that died without being ritually slaughtered (dhkah), with a disagreement as to whether this dislike was a prohibition (tahrim) or a mere discouragement (tanzih). However, they permitted the use of ivory from an elephant that was ritually slaughtered. As for the Hanafis, they permitted its sale and use, based on the opinion of its purity.