Puranic scriptures contain occasional references to "ansh" – literally 'portion, or avatars of Shiva', but the idea of Shiva avatars is not universally accepted in Saivism. The Linga Purana mentions twenty-eight forms of Shiva which are sometimes seen as avatars, however such mention is unusual and the avatars of Shiva is relatively rare in Shaivism compared to the well emphasized concept of Vishnu avatars in Vaishnavism. Some Vaishnava literature reverentially link Shiva to characters in its mythologies. For example, in the "Hanuman Chalisa", Hanuman is identified as the eleventh avatar of Shiva. The "Bhagavata Purana" and the "Vishnu Purana" claim sage Durvasa to be a portion of Shiva. Some medieval era writers have called the Advaita Vedanta philosopher Adi Shankara an incarnation of Shiva.