Here are 6 Bible verses about loving your siblings from the Old and New Testaments of the Holy Bible (King James Version), sorted from most to least relevant.
1 John 4:21 KJV
And this commandment have we from him, That he who loveth God love his brother also.
John 3:15 KJV
That whosoever believeth in him should not perish, but have eternal life.
1 John 4:7 KJV
Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God.
1 John 3:15 KJV
Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him.
1 Peter 3:8 KJV
Finally, be ye all of one mind, having compassion one of another, love as brethren, be pitiful, be courteous:
John 13:34-35 KJV
A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another. By this shall all men know that ye are my disciples, if ye have love one to another.