A saying attributed to the Prophet, returning from a battle, speaks of returning from the lesser struggle to the greater, the struggle against the self. Though its authenticity is disputed, Sufis have taken it as the charter of their discipline: the purification of the nafs.
Greater struggle
Jihād al-nafs: the struggle against one’s own ego, which Sufi tradition calls the greater jihad.
Also: jihad al-nafs, greater jihad