Those who guard mouth and tongue guard themselves from trouble. 
(Proverbs 21:23)
(New American Bible, Revised Edition)

Let the peace of Christ control your hearts, the peace into which you were also called in one body. And be thankful!
(Colossians 3:15)
(New American Bible, Revised Edition)

This I command you: love one another.
(John 15:17)
(New American Bible, Revised Edition)

If you keep my commandments, you will remain in my love, just as I have kept my Father's commandments and remain in his love. I have told you this so that my joy may be in you and your joy may be complete.
(John 15:10-11)
(New American Bible, Revised Edition)

I am the vine, you are the branches. Whoever remains in me and I in him will bear much fruit.
(See John 15:5)
(New American Bible, Revised, Edition)

Peace I leave with you; my peace I give to you.
Not as the world gives do I give it to you.
Do not let your hearts be troubled or afraid.
(John 14:27)
(New American Bible, Revised Edition)

If you love me, you will keep my commandments.
(John 14:15)
(New American Bible, Revised Edition)

I give you a new commandment: love one another. As I have loved you, so you should also love one another. This is how all will know that you are my disciples, if you have love for one another.
(John 13:34-35)
(New American Bible, Revised Edition)

If you remain in my word, you will truly be my disciples, and you will know the truth, and the truth will set you free.
(John 8:31)
(New American Bible, Revised Edition)

I am the way and the truth and the life. No one comes to the Father except through me.
(John 14:6)
(New American Bible, Revised Edition)