Writing and sayings
Hazrat Nizamuddin Aulia collected the discourses of his Pir-o-murshid in a book called "Rahat-ul-Qulodo."
Some of the sayings of Hazrat Nizamuddin Aulia:
1. The wilayat (domain) of gnosis and faith can suffer decay. The wilayat of compassion can not.
2. The love of Aulia (saints) is stronger than their reason.
3. The lock of spiritual perfection has very many keys. All those keys are to be possessed. If one does not open it, others can.
4. He who has knowledge, reason, and love, is deserving to become a caliph of the Sufi sheikhs.