Mark 3:35
"For whosoever shall do the will of God, the same is my brother, and my sister, and mother."
Cross References (ranked by relevance)
Matthew 7:21
Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
John 7:17
If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.
James 1:25
But whoso looketh into the perfect law of liberty, and continueth therein, he being not a forgetful hearer, but a doer of the work, this man shall be blessed in his deed.