Tasawwuf is the Soul of Deen-e-Islam

Islamic beliefs, the details of Fiqah, actions, etiquette, and worships are the body of Islam. But, its Qalb and Rooh is Ikhlas and Ihsan, or Tasawwuf and Salook.

For example, all the Fuqha (Islamic Jurists) have written that backbiting does not break the fast. In other words, it does not damage the body of the worship. The fast does not break going by the rules of the Shariah. However, according to Sahi Hadees, the soul of the fast leaves it if one indulges in backbiting. Obviously, the fast is as useless as a body without a soul.

This reality can only be acquired through Tasawwuf.

Dalail-us-Salook