The colour identity of  Rhys the Exiled is Green and Black.

As per the Commander colour identity rules:


  A card's colour identity is its colour plus the colour of any mana symbols in the card's rules text.


The colour doesn't have to be just in the casting cost (which determines the card's colour), any mana symbol cost in the rules text counts towards the card's colour identity.

See also Comprehensive Rule 903.4: 


  903.4. The Commander variant uses color identity to determine what cards can be in a deck with a certain commander. The color identity of a card is the color or colors of any mana symbols in that card's mana cost or rules text, plus any colors defined by its characteristic-defining abilities (see rule 604.3) or color indicator (see rule 204).
  Example: Bosh, Iron Golem is a legendary artifact creature with mana cost {8} and the ability "{3}{R}, Sacrifice an artifact: Bosh, Iron Golem deals damage equal to the sacrificed artifact's converted mana cost to target creature or player." Bosh's color identity is red.


Is the ability cost of the commander part of the color identity?
It seems rather basic, but I'm having trouble finding verses that say to read God's Word often. It seems like something that Paul said quite a few times, and it's obviously a good thing, but I can't find any specific verses. Can someone help me?
