Romans 13: 8 - 10
8 Owe no one anything, except to love one another; for he who loves his neighbor has fulfilled the law.
9 The commandments, "You shall not commit adultery, You shall not kill, You shall not steal, You shall not covet," and any other commandment, are summed up in this sentence, "You shall love your neighbor as yourself."
10 Love does no wrong to a neighbor; therefore love is the fulfilling of the law.

EWTN