“This is how all will know that you are my disciples, if you have love for one another.” (John 13:35)
“Beloved, let us love one another, because love is of God; everyone who loves is begotten by God and knows God.” (I John 4:7)
“In this way we know that we love the children of God when we love God and obey his commandments. For the love of God is this, that we keep his commandments. And his commandments are not burdensome” (I John 5:2,3)
“Let the man truly possessed by the love of Christ keep his commandments.” St. Clement I, pope AD 89 -99.