Endurance

To endure means to stick to it, to have fortitude and not stray away.  This is as aspect of faith and Jesus requires it for salvation: "The one who endures to the end will be saved." (Mark 13:13).  It usually has an aspect of enduring through difficulty, like a trial or persecution.

There was probably some minor persecution Ephesus endured because of holding with Jesus.  Jesus commends them for their faithfulness to him in this.

Endurance is an important aspect of faith in Revelation (Revelation 2:2, 3, 19; 3:10; 13:10; 14:12)