Here are 2 Bible verses about loving your sister, curated from both the Old and New Testaments of the Holy Bible, King James Version, arranged from most to least relevant.
John 15:12 KJV
12 This is my commandment, That ye love one another, as I have loved you.
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John 15:22 KJV
22 If I had not come and spoken unto them, they had not had sin: but now they have no cloak for their sin.