Like Ualaa says, you need the Insight Seal active and then all your melee attacks including autoattacks will give a heal of 30% of your damage to damaged party members.

Seal
http://www.wowhead.com/spell=20165

Glyph: Using melee attacks while using Seal of Insight heals a nearby injured friendly target, excluding the Paladin, within 30 yards for 30% of damage dealt.
http://www.wowhead.com/spell=20165