"And it came to pass, when he had made an end of speaking unto Saul, that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul.
And Saul took him that day, and would let him go no more home to his father's house.
Then Jonathan and David made a covenant, because he loved him as his own soul."
1 Samuel 18:1-3

"A man of many companions may come to ruin,
but there is a friend who sticks closer than a brother."
Proverbs 18:24

"Do not associate with a man given to anger;
Or go with a hot-tempered man,
Or you will learn his ways
And find a snare for yourself."
Proverbs 22:24-25

"If you find honey, eat just enough—
too much of it, and you will vomit.

Seldom set foot in your neighbor's house—
too much of you, and he will hate you."

Proverbs 25:16-17

"Better is open rebuke
than hidden love.

Wounds from a friend can be trusted,
but an enemy multiplies kisses."

Proverbs 27:5-6

Two are better than one,
because they have a good return for their work:

If one falls down,
his friend can help him up.
But pity the man who falls
and has no one to help him up!"

Ecclesiastes 4:9-10 

"This is My commandment, that you love one another as I have loved you. Greater love has no one than this, than to lay down one’s life for his friends. You are My friends if you do whatever I command you. No longer do I call you servants, for a servant does not know what his master is doing; but I have called you friends, for all things that I heard from My Father I have made known to you."
John 15:12-15

"A friend loves at all times,
And a brother is born for adversity."
Prov 17:17

"After David had finished talking with Saul, Jonathan became one in spirit with David, and he loved him as himself."
1 Sam 18:1

Two are better than one,
because they have a good return for their work:

If one falls down,
his friend can help him up.
But pity the man who falls
and has no one to help him up!

Also, if two lie down together, they will keep warm.
But how can one keep warm alone?

Though one may be overpowered,
two can defend themselves.
A cord of three strands is not quickly broken.

Eccl 4:9-12

"Rejoice with them that do rejoice, and weep with them that weep."
Rom 12:15

"Faithful are the wounds if a friend; but the kisses of an enemy are deceitful."
Prov 27:6

"A man that hath friends must show himself friendly: and there is a friend that sticketh closer than a brother."
Prov 18:24