Mark 12:28-31

One of the teachers of the law came and heard them debating.
   Noticing that Jesus had given them a good answer, he asked
   him, "Of all the commandments, which is the most important?"
   "The most important one," answered Jesus, "is this: `Hear, O
   Israel, the Lord our God, the Lord is one. Love the Lord
   your God with all your heart and with all your soul and with
   all your mind and with all your strength.' The second is
   this: `Love your neighbor as yourself.' There is no
   commandment greater than these."

   Mark 12:28-31