Why did hades first agree to return eurydice to orpheus?

Hades initially agreed to return Eurydice to Orpheus as a test of Orpheus's love and faith. He was intrigued by Orpheus's extraordinary musical talent, which had the power to move even the hearts of the dead. By allowing Orpheus to retrieve Eurydice, Hades sought to see if Orpheus would trust in the conditions set forth and not look back at her until they reached the surface. This agreement reflects the themes of trust, love, and the trials that often accompany them in mythology.