We by this time know that the whole happiness and grief is mind's creation.

Mind is responsible for making concepts and concepts are fundamental in experience of happiness or grief.

Hence we need to pay a closer attention to mind regarding its thought and concepts. Friendship is one such concept.

We develop friendship with those with whom our likes and dislikes match.

We need to very careful in our friend selection. Our journey after death depends on our state of mind and our state of mind is affected by thoughts of our friend with whom we are associated.