Imam Ali (AS) said:

If you think I doubt fighting with enemies from Shaam (Damascus); swear to Allah (SWT), every day that I delay the war is because I wish some of them join us and be guided. So that in between darkness and obscurity they can see my light and rush towards me, and this is better for me than killing them whilst they are misguided; although in that case they will also be getting into difficulty for their sins [1].

[1] Nahjul Balaghah, Sermon 55.

Source: en.shafaqna.com