My dads best friend just passed away

My dads friend just passed and I want to know what I could do or say to make him fell better

you could either a.) use the cliches by saying things like "He is in a better place" or "Think about the good times" or b.) go with the idea that nothing you can say can make him feel better right now. He just had a terrible thing happen to him as well as his friend.

Just let him know you are there for him, thats pretty much all you can do. Unfortunately theres nothing you can really do or say to make him feel all better.

Giving support to a grieving friend.

Be available.

Remember that your friend is in a very different place emotionally.

If you're not sure what to say or do, just ask. Say, "Do you feel like talking about this right now?" If they do, be there for them.

If they don't want to discuss their heartache, don't press the issue. Let them know that you are there for them regardless.

Don't treat your friend like an invalid. Encourage him or her to get out and get busy doing day-to-day activities.

Be supportive, but not smothering.

Recognize that you may need your own support system - prayer helps - Sometimes you can give support, and other times you'll need to receive it. Don't expect yourself to always be the leader.

Watch out for a shift into depression. If you see your friend withdrawing into an emotion fetal position, it's time to intervene.

For starters, I'm sorry that happened.
I don't know what you could say/do to make him feel better.
That was his best friend, so it will be hard.
Just give him time, and let him know you're there for him, and let him know you love him.
That's the most important thing. But he WILL be sad, and there's nothing you could do to change that, but he needs you right now.