While I can't cite the specifics, almost every UL standard I've seen refers to two
principles: mechanical damage and strain relief.
A simple plastic bushing, or a chase nipple, would suffice to protect these wires from being damaged by rubbing against the hole.
Being internal to the enclosure, I don't think there's a need for a strain relief fitting- though a "romex" connector might provide that.
Since this is already installed, the easiest thing is to install a plastic bushing, by first cutting one side.